What Affects Email Deliverability & 26 Tips for Better Campaigns

You send a fantastic email campaign, and can't wait to see the results. But when you open the reports, you're crushed to see that only a tiny fraction of your recipients ever opened your emails. What went wrong? While there are several potential explanations, one of the most common culprits is poor inbox delivery. Also known as "email deliverability," this metric measures the percentage of emails that reach their intended destination—inbox or spam folder. Recipients never see emails that end up in the spam folder or get filtered out and, therefore, can't achieve their goals, whether boosting sales, generating leads, or improving audience engagement. In this article, we'll cover what affects email deliverability to help you get your emails back on track so they land in recipients' inboxes, boosting engagement, conversions, and the overall success of your email campaigns.

Getting your emails to the inbox requires a solid email infrastructure. Inframail's email infrastructure helps you build a healthy sender reputation so your emails get the attention they deserve.

What is Email Deliverability and Its Importance

phone with no mails - What Affects Email Deliverability

Email deliverability is the rate at which your email makes it into recipient inboxes. An email deliverability rate can be lower when an email bounces or gets automatically filtered into a spam folder. Imagine you send mail to a friend with a missing sender name. The post could end up in the trash because of the unknown sender. Similarly, emails may get delivered to the recipient’s email address but in a spam or marketing folder.

‘Email deliverability’ may often be confused with ‘email delivery.’ While both terms refer to email delivery, there is a striking difference between them.

Email Delivery vs. Email Deliverability

Email delivery measures the number of emails delivered successfully, regardless of the folder. It tells if the recipient’s mail server has accepted the email file and offered it to the receiver. It calculates the percentage of emails that didn’t bounce out of the sent emails.

Email deliverability is akin to the number of emails that reach the right destination. Also known as inbox placement, it calculates the percentage of emails that get delivered to the priority inbox. For example, the deliverability rate of 100 emails, out of which 33 were in the spam folder, is 66%.

Key Differences Between Email Delivery and Email Deliverability: Causes, Challenges, and How to Address Them

A straightforward summary of this email delivery vs. email deliverability comparison is as follows:

Email delivery = How many emails were delivered?

Email deliverability = How many emails were delivered to the recipient’s inbox?

Delivery issues may be due to the following:

Faulty email addresses
Problems with your infrastructure
Too much negative feedback on the email address

Deliverability issues arise due to outdated sending and permission practices, violating a law, or receiving too many spam labels by the receivers.

Why Does Email Deliverability Matter So Much?

Email deliverability is crucial for higher ROI. For every $1 spent, email gives an ROI of around $36. Even if the email delivery rate is around 97% for the 1,000 emails sent, there are still 30 emails that bounce back. Now, consider the open rates. The open rates might oscillate around 30%-40%.

One primary reason for low open rates could be email deliverability. Emails in the spam or promotional folders have lower open rates because they are often overlooked. For email marketers, getting higher open rates is imperative. To ensure that, it is essential that every email that you send ends up in the inbox.

What Affects Email Deliverability?

Sender Reputation: The Most Important Factor That Affects Email Deliverability

Email servers assign a sender score to you based on the quality of your past email campaigns. If many recipients mark your emails as spam, or if your messages bounce back from:

Unvalidated email addresses
Your sender’s reputation declines
Undermining your email deliverability

Besides sender reputation, email deliverability also relies on the following:

Domain Reputation

It’s the reputation your domain earns from an email service provider based on how recipients engage with your emails. If more contacts open and respond to your emails, you earn a positive domain reputation, and if more prospects tag your email as spam, your domain reputation declines.  

IP Address Reputation

It measures how well an IP address behaves. If an IP address sends genuine, spam-free emails, it earns a positive IP reputation, and if it’s associated with malware and bulk spam mail, it gets a negative IP reputation.

Email Authentication: Proving You're Not a Spammy Robot

Email authentication is setting up authentication protocols to ensure the email service provider that you’re the one sending the outreach emails and they can be trusted.

The three major authentication protocols are as follows:  

SPF (Sender Policy Framework)

The Sender Policy Framework protects you and your recipients from spam and spoofing. It enables you to add a list of senders authorized to send email from your domain. For instance, using an SPF record, you can use separate email APIs or software tools for your marketing and sales emails and add both services as approved senders.

This lets your contacts know that the messages are authentic and trustworthy.

DKIM (DomainKeys Identified Mail)

DKIM uses digital signatures and encryption keys to validate your emails and prevent recipients from replying to illegitimate messages.  

DMARC (Domain-based Message Authentication Reporting & Conformance)

DMARC adds an extra layer of security to your emails – an alignment test. It also lets you warn recipient servers about a failed email test so that they can discard or quarantine a suspicious email.

Email List Quality: The More You Know

Maintaining a high-quality contact list is paramount in ensuring a smooth and hassle-free email delivery. You can retain your active subscribers by gathering a targeted email list and sending personalized campaigns relevant to users on that list. At the same time, you could win back my inactive subscribers through various re-engagement campaigns. If people need to be more actively engaging with your campaign, reduce the emails you send them or scrub my list.

This is because many inactive subscribers on my list can impact my delivery. If my subscribers have yet to respond after a reconfirmation campaign, consider deleting those inactive IDs. While it could be painful to trim down my hard-earned list, in the long run, you will thank yourself because the better the list quality, the better the engagement rate.

Email Volume and Frequency: Don’t Go Overboard

Spammers usually send blasts of emails to recipients from a new domain before the recipient mailbox provider can identify and block them. When you start your outreach campaign from a fresh domain, sending bulk emails can trigger a spam filter. Instead, start by sending a small volume of messages at regular intervals to build up your reputation.

Maintain the cadence during your initial cold emailing days and gradually increase the number of emails. Besides email volume, the frequency of sending them also affects deliverability. Email frequency is not fixed and evolves as you build your sender reputation. Start with a low frequency of emails and then increase it depending on prospect engagement.

Email Subject Line and Content: Make It Appealing and Legit

Most recipients will open your email depending on its subject line. A misleading or clickbait-y subject line can turn off readers and trigger them to mark your messages as spam. An email service provider like Gmail can even identify spammy keywords in your subject line and send your emails to spam. Besides your subject line, your email’s content must also be free of spammy words to get past most spam filters.

The content of your marketing email is a critical factor in determining its deliverability. This is mainly because spam filters of popular email service providers analyze the content, headers, message texts, and attachments to identify and block potentially malicious content. Sadly, some reports state that legitimate emails end up in spam folders from:

Pharmaceutical companies
Dating sites
Mortgages

Evolution of Spam Filters: From Basic Pattern Matching to Advanced Collaborative Filtering and Their Potential Drawbacks

The first few generations of spam filters were relatively limited and straightforward. For example, they could match and identify only specific patterns of emails. Recent filtering techniques have introduced more advanced collaborative filters whereby multiple services and sites can contribute spam reports to a centralized service.

One problem with this collaborative filter technology is that if a filter identifies a particular message as spam and submits the report to a centralized service, all the other service providers take up the same information without asking questions.

Email Engagement Metrics: Keep Track of Performance

You can assess the success of your email campaign using these key metrics:  

Spam Complaint Rate

The number of email recipients marked as spam out of all your outbound messages. The industry-acceptable spam rate is 0.1%. Anything above that will lower your deliverability.  

Bounce Rate

The percentage of your emails that bounce back or are rejected by recipients. This usually happens when:

You email a risky contact
Who could be an invalid
A spam trap
Someone with a strong filter on incoming emails. (You’ll want this rate below 2.8% for cold emails.)

Response Rate

It’s a metric of the number of emails that receive a response out of the total emails sent. A reasonable response rate is around 10%, but 5% might be a reasonable target in some segments.  

Inbox Placement Rate

The percentage of outbound emails that reach a prospect’s primary inbox out of your outgoing emails. (meaning they didn’t land in spam or junk folders). You’ll want this to be above 90%.  

Open Rate

It’s the percentage of emails your recipients open. Although this isn’t as accurate as it used to be, generally, you’ll want this rate above 50% and need to watch for declines as an early signal of deliverability issues.

Unsubscribe and Double Opt-in Provisions: Give Them an Out

Only some of your contacts are interested in your emails, and they prefer a way out to stop receiving your emails. Including an option to unsubscribe gives your prospects a chance to stop receiving your emails. If you don’t do so, uninterested contacts might be more likely to report your emails as spam to stop receiving them and dent my deliverability.

Likewise, for prospects who’ve subscribed to your email list, adding another opt-in link to confirm their subscription ensures that they’re genuinely interested and not likely to flag your emails. (this is called double opt-in).

Spam Trap Issues: Avoid Getting Caught

Spam traps are fraud management tools used by internet service providers, anti-spam organizations, etc., to identify and block emails from spammers. Spam traps often look like regular email addresses, but they cannot be used for communication as they do not belong to any person or organization.

Spam traps can cause your domain or IP address to be denied, affecting your email deliverability rates and sender reputation. You may not be a spammer, but it is essential to understand the potential dangers hidden in spam traps and avoid adding them to your contact list.

Email Bounces: Don't Let Them Get Out of Control

Email bounces occur when messages are not delivered to the recipient's inbox. Email service providers want their customers to see that brands follow good practices to acquire subscribers, so they opt for two different methods.

ESP brands send too many emails to IDs that don't exist. When emails are delivered to non-existing IDs, those emails experience hard bounces. In such a case, email service providers block those IDs to ensure that non-future emails will be delivered to them. Keep in mind that if you experience more than 2% of hard bounces, it will affect your deliverability.

Mobile-friendly Designs: Adapt to Your Audience

Gone are the days when users sat in front of their computers to check their emails. The 21st century marked the smartphone revolution. Users prefer to check their emails on portable devices such as smartphones or tablets. Research has indicated that over 43% of emails are opened through a mobile device. The rate is so high that it is common for companies to make a mobile-friendly design while sending emails.

Best Practices for Creating Mobile-Friendly Emails to Boost Deliverability and Subscriber Engagement

Imagine that your marketing emails must load correctly on a mobile device. In this scenario, there is a high chance it will turn off your loyal subscribers, eventually losing them to your competitors. To improve your email deliverability rates, you should adopt design templates that are easier to view on mobile devices.

Some techniques to adopt for producing a mobile-friendly design include:  Use single-column templates  The width of your email template should be 600 pixels  Provide a clear CTA button  Use large fonts  Display small images, etc.  Use URL shorteners.

Email Infrastructure: It’s About More Than Just Content

Email deliverability largely depends on the software and hardware systems despite everything being on the cloud. The email system works much like a real-life postal service system; after you write a letter and dispatch it for delivery, the postal services, the people who sort the letters, and the delivery persons deliver the posts to the receiver’s doorstep.

In the same way, email deliverability depends on three hardware and software structures: mail servers, agents, and IP addresses. If you have a high email volume, you need a dedicated IP that provides a robust and seamless email infrastructure.

Levels of Engagement: Pay Attention to Feedback

Email service providers pay attention to positive and negative feedback on an email. The input is usually based on the time spent reading the mail, CTR, and open rates. Research has shown that positive engagement is an essential factor affecting deliverability.

Thus, senders must manage their inactive subscribers by reducing the emails sent to them and eventually deleting them from the list. Sending more personalized and segmented email campaigns can boost the engagement rate of the mail, which also positively impacts deliverability.

26 Ways to Improve Email Deliverability Rate

notepad and keyboard - What Affects Email Deliverability

1. Don't Buy or Rent Email Lists

Resist the urge to buy or rent email lists. Yes, you can legally rent and purchase lists of people who have agreed to email communications—but it's never a good idea. Not only is it a dirty email marketing tactic that goes against the Terms of Service for your email service provider, but these people don‘t know you—and it’s likely they won't even want your emails. In other words, there‘s a good chance they’ll mark you as spam. Plus, be honest… high-quality email addresses are never for sale.

2. Don't Email People Who Have Bounced Repeatedly

Bounce rates are one of the key factors internet service providers (ISPs) use to determine an email sender‘s reputation, so having too many hard bounces can cause them to stop allowing your emails in folks’ inboxes. Hard bounces result from non-existent email addresses, domains, and typos in the recipient’s email address. Re-attempts to send duplicate emails will further aggravate the bounce rates, which is a red flag for ISPs.

3. Avoid All Caps in Your Emails

Using caps in email subject lines lowers the response rate by 30%. It looks like you are shouting at your audience, making your email less readable and disinteresting. It's annoying and can seem spammy. Instead of using disruptive tactics like all caps to get people's attention, try personalizing your emails and using catchy and delightful language. (Read this blog post on how to write compelling emails for more tips.)

4. Avoid Excessive Punctuation

Even the smallest of symbols can drastically change the destiny of your email. Using too many exclamation points seems unprofessional and dominating. You don’t need any fillers to get your emails noticed. And when 69% of email recipients report email as spam based solely on the subject line, you'll want to avoid triggers like this as much as possible. Plus, asking for punctuation to do a word’s job can dilute your message. Use this flowchart as a gut check when tempted to use an exclamation point in an email (or anywhere).

5. Avoid Rich Media Like Video and Flash

Most email clients cannot view rich media like Flash or video embeds by default. As for JavaScript and other dynamic scripts, even if a spam filter enables your email to go through, most email clients won't allow these scripts to function — so avoid using them altogether.

Instead, use an image of your video player (with a play button) that links to the rich media on a website page. If you want to communicate your video idea better, you can incorporate a GIF (with a link) and track the click-through rates thereafter. To clear your doubts about embedding videos in emails, read our guide on embedding videos in emails.

6. Avoid Attachments to Your Emails

Yes. The statement sounds vague, but including the attachments to your cold emails is never a good idea. An email with a short wall of text and all the first-hand information in the attachment could be left unnoticed. Also, the receivers consider the first emails with attachments spam or malicious.

This worsens the chances of getting your email to the spam folder. Upload the attachment to your website and link to the file location in your email using a practical call-to-action button. This will minimize the chance of being blocked by spam filters and decrease your email’s load time.

7. Don't Use Spam Trigger Words

One of the easiest ways to avoid spam filters is by carefully choosing the words you use in your email's subject line. A good rule of thumb is this: If it sounds like something a used car salesman would say, it's probably a spam trigger word. Think:

Free
Guarantee
No obligation, and so on.

Instead of using these trigger words, be creative, engaging, and informative—without giving too much away. Some better ideas for subject lines include:

“Hi [name], [question]?”
“Did you get what you were looking for?”
“You are not alone.”
“Feeling blue? Like puppies?”

8. Don't Forget to Use Spell Check

Spelling and grammar mistakes are the most embarrassing email offenses. According to a report by Grammarly, around 93% of the respondents made email typos and blunders. Of this, 63% committed embarrassing typos, while the recipients misunderstood 50%. To maintain good email etiquette, you must avoid typos. And, it‘s easy for little spelling mistakes to slip by — especially when you’re self-editing. Read this post to learn the most common spelling and grammar mistakes so you never make them again.

9. Avoid Jamming Your Email Copy with Keywords

Keyword-stuffing your emails means shoving as many keywords into your emails as possible. There‘s a reason Google gives a lower rank to web pages stuffed with keywords—because it harms user experience. To make it more likely folks will open your emails and not mark them as spam, write your emails for humans, not robots. Copywriting that makes people want to take action is both simple and compelling. Use casual language, colloquial expressions, and even personal anecdotes to make your writing sound more personable and relatable.

10. Avoid Using Too Many Images or Huge Images

Using one large image as your entire email, or too many images in general, tends to end up in recipients' spam folders. Most email recipients set their spam trigger criteria to filter heavily loaded images. To prevent long email load times, you’ll also want to make your image file sizes as small as possible without losing their visual integrity. Microsoft Outlook doesn't recognize background images, so you may want to avoid those and use a background color instead

11. Keep Your Email Lists Current and Clean

Even if your list is entirely built on valid opt-ins, you risk being branded a “spammer” if you don’t practice proper email hygiene. Why? Because internet service providers (ISPs) base complaint rates on active subscribers, not total subscribers.

Also, expired email addresses can become SPAM traps, meaning that even if you legitimately acquired emails, the abandoned addresses that haven't engaged in years may have morphed into spam traps. Hitting even just one spam trap can cause deliverability problems. Expired email addresses can also turn into unknown users (bounces).

The Importance of Email List Hygiene: Reducing Unknown Accounts to Protect Sender Reputation and Improve Deliverability

If you hit unknown accounts at a rate higher than 5%, then ISPs will see you as someone with lousy email hygiene. The result? They‘ll make it harder for your emails to reach people‘s inboxes, and your overall sender reputation will drop, leading to even more trouble reaching them.

Keeping your email lists current and clean will decrease the likelihood that people will flag your emails as spam. You can identify inactive subscribers and expired email addresses with metrics such as:

Opens
Clicks
Website activity

12. Re-Engage With Inactive Subscribers

Even if your email list is clean, the task is still half done. “Graymail” refers to emails people technically opt-in to receive but don‘t want. This leads them to become less active or inactive altogether. Although it’s not considered spam, sending graymail is problematic because it can hurt the deliverability of your email overall.

Tipped off by low engagement rates, ISPs, and inbox providers may deliver emails from known graymail senders straight to recipients‘ "junk" folders. Technically, the email gets sent (and can even appear to have been delivered), but it’s not necessarily seen.

Re-engagement Strategies: How to Win Back Inactive Subscribers and Strengthen Email Campaign Performance

Keep track of inactive and infrequently active subscribers and develop re-engagement campaigns for contacts who have stopped engaging with your messages. For example, you could set conditions such as the length of time since their last form submission, website visit, or email click, triggering the email when it’s been a while since they last engaged with you.

You can send them an exclusive offer or coupon in your workflow to get them excited about your company again. You can also ask for feedback by sending a quick survey to see what they want in your emails.

13. Make Use of Double Opt-Ins

Double opt-in confirmation is one of the best ways to reduce email bounce rates. Double opt-in means that after someone subscribes to your email list, you send them a follow-up email with a confirmation link, ensuring they want to receive your email communications. When you use double opt-in, your email lists will be much more qualified, and your subscribers will be much more engaged.

14. Ask Your Subscribers to Add You to Their Address Book

Spam filters are more aggressive than ever—so much so that sometimes, the emails people value and want to read still end up in their spam boxes. Ensure your emails get delivered by telling the subscriber’s email server that your email is safe enough to end up in their inbox. Thrivecart does an excellent job of making this happen. They specify why adding their email address is essential for the subscribers. Spam filters will back off when subscribers add you to their address book.

15. Include a Clear Unsubscribe Link and Physical Address in the Footer

There could be many reasons why your email subscribers want to opt out of your email list. It is always a good practice to allow people to unsubscribe to maintain list hygiene. In your marketing emails, you must include a way for folks to unsubscribe from your email list, either by simply sending a reply email or by clicking no more than one level deep to reach a page from which they can unsubscribe.

Your chosen method is entirely up to you if the information is clear and easy to locate. If you wish to evoke the subscriber’s interest, here are the best unsubscribe button ideas to save my subscribers. The most common place for these unsubscribe CTAs is in the footer of your email, so users tend to know to look for it there — which makes for a better user experience. Here‘s an example from one of HubSpot’s emails:

16. Use a Familiar Sender Name

Besides the subject line, the sender’s name is the second most crucial factor that gets your email read and opened. 45% of emails are opened because of the sender’s name. People are so inundated with SPAM that they hesitate to open emails from unfamiliar senders. Make sure recipients can recognize you as your sender by using your brand name. After establishing trust among the subscribers, create a personalization using the sender’s name.

Recipients are typically more likely to trust a personalized sender name and email address than a generic one. Use the original domain name instead of sending emails from Gmail, AOL, and Yahoo. I love this example from Userpilot that uses the sender’s name to create a sense of personalization. The email is sent on behalf of their content head, Emilia, using personal pronouns like ‘We’ and ‘I.’

17. Offer Recipients Both an HTML and a Plain Text Version of Your Emails

Plain text emails are simply emails void of any formatting, while HTML (HyperText Markup Language) emails use formatting that lets you design more beautiful emails with attractive visual components. By offering a plain text and HTML version of a single email, you‘re indicating your legitimacy to ISPs and making your emails more reader-friendly. Most email marketing tools will let you easily create plain-text versions within their email editor, so take those five extra minutes to make and optimize the plain-text version of your email. Also, ensure the HTML version is coded correctly: If your HTML has broken tags, the email provider and users might mark it as spam.

18. Allow People to View Your Email in a Web Browser

Even after every step is taken to ensure proper email design, an email client can still display an email poorly. Each client displays emails differently, and some clients have certain features that may render only partially in others. The way an email looks in Gmail might be different than how it looks in Yahoo or Outlook. Hence, it is crucial to include a link in every email so that the email can be viewed as a web page.

19. Include Alt Text in Your Email Images

Many email clients block images by default. When someone opens your email, the images will load if they click a button to show them or change their default settings. Adding alt text to your images helps recipients understand your message even if they can't see the pictures. This is especially bad if you use an image as a call-to-action. Without alt text, a “turned off” image will look like this: When you add alt text to the image, recipients will still know where to click to complete the action.

20. Keep Your Emails Short and Sweet

Too much copy is another red flag for spam filters. People generally like concise emails better. Everyone’s busy, and their inbox is complete, so why worsen things? Writing like a human is one of the best ways to keep things short and sweet. Writing your email like you were talking to someone in real life makes it feel much more approachable and relevant. If you must write a lengthier email, break it into multiple paragraphs. Giving visual breaks and composing the email with a clear introduction, middle, and conclusion will make it much easier for your reader.

21. Test Your Emails Before Sending Them

There are many email clients out there these days that email marketers have to consider when creating emails. We also must consider mobile users; 41% of people read email on their mobile devices. Since different email clients view emails differently, use the A/B testing technique to test your email copies. While it may be time-consuming to test your emails for all email clients, you'll want to test them for the ones your audience uses the most.

Optimizing Emails for Top Email Clients: Why Testing Across Platforms Matters for Campaign Success

According to Litmus' research of 1.06 billion emails opened, the top five email clients are:

Apple iPhone's Mail app (28% of users)
Gmail (16% of users)
Apple iPad's Mail app (11% of users)
Google Android's Mail app (9% of users)
Outlook (9% of users)

If your email marketing tool lets you go ahead and preview what your email looks like in different email clients and devices that are popular with your audience. You should also send out a test version of your email before sending out the real deal to ensure it works properly.

22. Get an Email Sender Accreditation From a Third Party

Sender accreditation is a third-party process of verifying email senders and requiring them to follow specific usage guidelines. This badge of trust adds your company email address to a trusted listing that ISPs refer to allow certain emails to bypass email filters.

23. Monitor the Reputation of Your Sender's IP Address

Your emails‘ deliverability depends mainly on your IP address’s reputation. If you‘re sending emails from an IP address with a poor reputation, your emails are far less likely to be successfully delivered to senders’ inboxs. DNSchecker.org lets you check on whether or not you are a blacklisted sender—something many unlucky email marketers aren't even aware of.

24. Stay Up-to-Date With Anti-Spam Laws, Spam Filters, and IPs Filter Technology

Email marketing constantly evolves, and staying in the know helps ensure you always follow best practices—and the law. Responsible and legitimate email marketers regularly read up on:

Email-sending laws
ISP behavior
Spam filter technology

If you need more information, consult your company’s legal department or a trusted lawyer to ensure you follow the law.

25. Make Emails Personal

Subscribers opt-in to receive your messages because they value your brand. Personalization makes subscribers feel:

Recognized
Boosting engagement
Conversions
Loyalty

Engage subscribers with tactics like:

Combining segmentation and personalization to align with where subscribers are in their journey, tailoring future messages based on their interests.
Dynamic content populates messages with product recommendations, exclusive offers, or relevant weather-based updates.
Engage subscribers with interactive elements, like polls or surveys, to make your emails more engaging and valuable.

26. Monitor Feedback Loops

Email feedback loops provide insights into how your campaigns perform post-send, helping you fine-tune your strategy. Review these metrics regularly with your team to quickly adapt to trends and address emerging deliverability challenges.

Start Buying Domains Now and Setup Your Email Infrastructure Today

Email deliverability refers to delivering emails to the recipient’s inbox rather than their spam folder or other tabs like "Promotions" or "Updates." A high email deliverability rate is fundamental for effective email marketing, as it determines how many of your sent emails reach your audience. As a rule of thumb, the higher your email deliverability rate, the better.

Email Deliverability vs. Deliverability Rate: Understanding the Difference and Why Inbox Placement Matters Most

For instance, an email deliverability rate of 90% means that out of 100 people you sent emails to, only 10 were in the spam folder. Email deliverability differs from email deliverability rate, which measures the percentage of emails reaching the intended destination. It’s possible to have a high email deliverability rate while the deliverability itself is low.

This happens when emails are reaching the wrong destination. In the example above, if you had a high email deliverability rate of 90% but only ten emails reached the inbox, with the rest going to the spam folder, you’d have a serious deliverability problem. What truly matters is getting as many emails as possible to the right place: the inbox.

What Affects Email Deliverability?

Several factors affect email deliverability, including:

Sender reputation
Domain authentication
Email engagement

Each factor has sub-factors that can help or hurt your email deliverability. For instance, a sender’s reputation is determined by your history of sending emails, and consistent and proper email practices can improve it.

At the same time, domain authentication helps establish your legitimacy as a sender so that receiving servers can identify you and trust that your emails are safe. Email engagement, on the other hand, is measured by how recipients interact with your emails and can be improved by creating relevant and targeted content that your audience cares about.

You send a fantastic email campaign, and can't wait to see the results. But when you open the reports, you're crushed to see that only a tiny fraction of your recipients ever opened your emails. What went wrong? While there are several potential explanations, one of the most common culprits is poor inbox delivery. Also known as "email deliverability," this metric measures the percentage of emails that reach their intended destination—inbox or spam folder. Recipients never see emails that end up in the spam folder or get filtered out and, therefore, can't achieve their goals, whether boosting sales, generating leads, or improving audience engagement. In this article, we'll cover what affects email deliverability to help you get your emails back on track so they land in recipients' inboxes, boosting engagement, conversions, and the overall success of your email campaigns.

Getting your emails to the inbox requires a solid email infrastructure. Inframail's email infrastructure helps you build a healthy sender reputation so your emails get the attention they deserve.

What is Email Deliverability and Its Importance

Email deliverability is the rate at which your email makes it into recipient inboxes. An email deliverability rate can be lower when an email bounces or gets automatically filtered into a spam folder. Imagine you send mail to a friend with a missing sender name. The post could end up in the trash because of the unknown sender. Similarly, emails may get delivered to the recipient’s email address but in a spam or marketing folder.

‘Email deliverability’ may often be confused with ‘email delivery.’ While both terms refer to email delivery, there is a striking difference between them.

Email Delivery vs. Email Deliverability

Email delivery measures the number of emails delivered successfully, regardless of the folder. It tells if the recipient’s mail server has accepted the email file and offered it to the receiver. It calculates the percentage of emails that didn’t bounce out of the sent emails.

Email deliverability is akin to the number of emails that reach the right destination. Also known as inbox placement, it calculates the percentage of emails that get delivered to the priority inbox. For example, the deliverability rate of 100 emails, out of which 33 were in the spam folder, is 66%.

Key Differences Between Email Delivery and Email Deliverability: Causes, Challenges, and How to Address Them

A straightforward summary of this email delivery vs. email deliverability comparison is as follows:

Email delivery = How many emails were delivered?

Email deliverability = How many emails were delivered to the recipient’s inbox?

Delivery issues may be due to the following:

Faulty email addresses
Problems with your infrastructure
Too much negative feedback on the email address

Deliverability issues arise due to outdated sending and permission practices, violating a law, or receiving too many spam labels by the receivers.

Why Does Email Deliverability Matter So Much?

Email deliverability is crucial for higher ROI. For every $1 spent, email gives an ROI of around $36. Even if the email delivery rate is around 97% for the 1,000 emails sent, there are still 30 emails that bounce back. Now, consider the open rates. The open rates might oscillate around 30%-40%.

One primary reason for low open rates could be email deliverability. Emails in the spam or promotional folders have lower open rates because they are often overlooked. For email marketers, getting higher open rates is imperative. To ensure that, it is essential that every email that you send ends up in the inbox.

What Affects Email Deliverability?

Sender Reputation: The Most Important Factor That Affects Email Deliverability

Email servers assign a sender score to you based on the quality of your past email campaigns. If many recipients mark your emails as spam, or if your messages bounce back from:

Unvalidated email addresses
Your sender’s reputation declines
Undermining your email deliverability

Besides sender reputation, email deliverability also relies on the following:

Domain Reputation

It’s the reputation your domain earns from an email service provider based on how recipients engage with your emails. If more contacts open and respond to your emails, you earn a positive domain reputation, and if more prospects tag your email as spam, your domain reputation declines.  

IP Address Reputation

It measures how well an IP address behaves. If an IP address sends genuine, spam-free emails, it earns a positive IP reputation, and if it’s associated with malware and bulk spam mail, it gets a negative IP reputation.

Email Authentication: Proving You're Not a Spammy Robot

Email authentication is setting up authentication protocols to ensure the email service provider that you’re the one sending the outreach emails and they can be trusted.

The three major authentication protocols are as follows:  

SPF (Sender Policy Framework)

The Sender Policy Framework protects you and your recipients from spam and spoofing. It enables you to add a list of senders authorized to send email from your domain. For instance, using an SPF record, you can use separate email APIs or software tools for your marketing and sales emails and add both services as approved senders.

This lets your contacts know that the messages are authentic and trustworthy.

DKIM (DomainKeys Identified Mail)

DKIM uses digital signatures and encryption keys to validate your emails and prevent recipients from replying to illegitimate messages.  

DMARC (Domain-based Message Authentication Reporting & Conformance)

DMARC adds an extra layer of security to your emails – an alignment test. It also lets you warn recipient servers about a failed email test so that they can discard or quarantine a suspicious email.

Email List Quality: The More You Know

Maintaining a high-quality contact list is paramount in ensuring a smooth and hassle-free email delivery. You can retain your active subscribers by gathering a targeted email list and sending personalized campaigns relevant to users on that list. At the same time, you could win back my inactive subscribers through various re-engagement campaigns. If people need to be more actively engaging with your campaign, reduce the emails you send them or scrub my list.

This is because many inactive subscribers on my list can impact my delivery. If my subscribers have yet to respond after a reconfirmation campaign, consider deleting those inactive IDs. While it could be painful to trim down my hard-earned list, in the long run, you will thank yourself because the better the list quality, the better the engagement rate.

Email Volume and Frequency: Don’t Go Overboard

Spammers usually send blasts of emails to recipients from a new domain before the recipient mailbox provider can identify and block them. When you start your outreach campaign from a fresh domain, sending bulk emails can trigger a spam filter. Instead, start by sending a small volume of messages at regular intervals to build up your reputation.

Maintain the cadence during your initial cold emailing days and gradually increase the number of emails. Besides email volume, the frequency of sending them also affects deliverability. Email frequency is not fixed and evolves as you build your sender reputation. Start with a low frequency of emails and then increase it depending on prospect engagement.

Email Subject Line and Content: Make It Appealing and Legit

Most recipients will open your email depending on its subject line. A misleading or clickbait-y subject line can turn off readers and trigger them to mark your messages as spam. An email service provider like Gmail can even identify spammy keywords in your subject line and send your emails to spam. Besides your subject line, your email’s content must also be free of spammy words to get past most spam filters.

The content of your marketing email is a critical factor in determining its deliverability. This is mainly because spam filters of popular email service providers analyze the content, headers, message texts, and attachments to identify and block potentially malicious content. Sadly, some reports state that legitimate emails end up in spam folders from:

Pharmaceutical companies
Dating sites
Mortgages

Evolution of Spam Filters: From Basic Pattern Matching to Advanced Collaborative Filtering and Their Potential Drawbacks

The first few generations of spam filters were relatively limited and straightforward. For example, they could match and identify only specific patterns of emails. Recent filtering techniques have introduced more advanced collaborative filters whereby multiple services and sites can contribute spam reports to a centralized service.

One problem with this collaborative filter technology is that if a filter identifies a particular message as spam and submits the report to a centralized service, all the other service providers take up the same information without asking questions.

Email Engagement Metrics: Keep Track of Performance

You can assess the success of your email campaign using these key metrics:  

Spam Complaint Rate

The number of email recipients marked as spam out of all your outbound messages. The industry-acceptable spam rate is 0.1%. Anything above that will lower your deliverability.  

Bounce Rate

The percentage of your emails that bounce back or are rejected by recipients. This usually happens when:

You email a risky contact
Who could be an invalid
A spam trap
Someone with a strong filter on incoming emails. (You’ll want this rate below 2.8% for cold emails.)

Response Rate

It’s a metric of the number of emails that receive a response out of the total emails sent. A reasonable response rate is around 10%, but 5% might be a reasonable target in some segments.  

Inbox Placement Rate

The percentage of outbound emails that reach a prospect’s primary inbox out of your outgoing emails. (meaning they didn’t land in spam or junk folders). You’ll want this to be above 90%.  

Open Rate

It’s the percentage of emails your recipients open. Although this isn’t as accurate as it used to be, generally, you’ll want this rate above 50% and need to watch for declines as an early signal of deliverability issues.

Unsubscribe and Double Opt-in Provisions: Give Them an Out

Only some of your contacts are interested in your emails, and they prefer a way out to stop receiving your emails. Including an option to unsubscribe gives your prospects a chance to stop receiving your emails. If you don’t do so, uninterested contacts might be more likely to report your emails as spam to stop receiving them and dent my deliverability.

Likewise, for prospects who’ve subscribed to your email list, adding another opt-in link to confirm their subscription ensures that they’re genuinely interested and not likely to flag your emails. (this is called double opt-in).

Spam Trap Issues: Avoid Getting Caught

Spam traps are fraud management tools used by internet service providers, anti-spam organizations, etc., to identify and block emails from spammers. Spam traps often look like regular email addresses, but they cannot be used for communication as they do not belong to any person or organization.

Spam traps can cause your domain or IP address to be denied, affecting your email deliverability rates and sender reputation. You may not be a spammer, but it is essential to understand the potential dangers hidden in spam traps and avoid adding them to your contact list.

Email Bounces: Don't Let Them Get Out of Control

Email bounces occur when messages are not delivered to the recipient's inbox. Email service providers want their customers to see that brands follow good practices to acquire subscribers, so they opt for two different methods.

ESP brands send too many emails to IDs that don't exist. When emails are delivered to non-existing IDs, those emails experience hard bounces. In such a case, email service providers block those IDs to ensure that non-future emails will be delivered to them. Keep in mind that if you experience more than 2% of hard bounces, it will affect your deliverability.

Mobile-friendly Designs: Adapt to Your Audience

Gone are the days when users sat in front of their computers to check their emails. The 21st century marked the smartphone revolution. Users prefer to check their emails on portable devices such as smartphones or tablets. Research has indicated that over 43% of emails are opened through a mobile device. The rate is so high that it is common for companies to make a mobile-friendly design while sending emails.

Best Practices for Creating Mobile-Friendly Emails to Boost Deliverability and Subscriber Engagement

Imagine that your marketing emails must load correctly on a mobile device. In this scenario, there is a high chance it will turn off your loyal subscribers, eventually losing them to your competitors. To improve your email deliverability rates, you should adopt design templates that are easier to view on mobile devices.

Some techniques to adopt for producing a mobile-friendly design include:  Use single-column templates  The width of your email template should be 600 pixels  Provide a clear CTA button  Use large fonts  Display small images, etc.  Use URL shorteners.

Email Infrastructure: It’s About More Than Just Content

Email deliverability largely depends on the software and hardware systems despite everything being on the cloud. The email system works much like a real-life postal service system; after you write a letter and dispatch it for delivery, the postal services, the people who sort the letters, and the delivery persons deliver the posts to the receiver’s doorstep.

In the same way, email deliverability depends on three hardware and software structures: mail servers, agents, and IP addresses. If you have a high email volume, you need a dedicated IP that provides a robust and seamless email infrastructure.

Levels of Engagement: Pay Attention to Feedback

Email service providers pay attention to positive and negative feedback on an email. The input is usually based on the time spent reading the mail, CTR, and open rates. Research has shown that positive engagement is an essential factor affecting deliverability.

Thus, senders must manage their inactive subscribers by reducing the emails sent to them and eventually deleting them from the list. Sending more personalized and segmented email campaigns can boost the engagement rate of the mail, which also positively impacts deliverability.

26 Ways to Improve Email Deliverability Rate

1. Don't Buy or Rent Email Lists

Resist the urge to buy or rent email lists. Yes, you can legally rent and purchase lists of people who have agreed to email communications—but it's never a good idea. Not only is it a dirty email marketing tactic that goes against the Terms of Service for your email service provider, but these people don‘t know you—and it’s likely they won't even want your emails. In other words, there‘s a good chance they’ll mark you as spam. Plus, be honest… high-quality email addresses are never for sale.

2. Don't Email People Who Have Bounced Repeatedly

Bounce rates are one of the key factors internet service providers (ISPs) use to determine an email sender‘s reputation, so having too many hard bounces can cause them to stop allowing your emails in folks’ inboxes. Hard bounces result from non-existent email addresses, domains, and typos in the recipient’s email address. Re-attempts to send duplicate emails will further aggravate the bounce rates, which is a red flag for ISPs.

3. Avoid All Caps in Your Emails

Using caps in email subject lines lowers the response rate by 30%. It looks like you are shouting at your audience, making your email less readable and disinteresting. It's annoying and can seem spammy. Instead of using disruptive tactics like all caps to get people's attention, try personalizing your emails and using catchy and delightful language. (Read this blog post on how to write compelling emails for more tips.)

4. Avoid Excessive Punctuation

Even the smallest of symbols can drastically change the destiny of your email. Using too many exclamation points seems unprofessional and dominating. You don’t need any fillers to get your emails noticed. And when 69% of email recipients report email as spam based solely on the subject line, you'll want to avoid triggers like this as much as possible. Plus, asking for punctuation to do a word’s job can dilute your message. Use this flowchart as a gut check when tempted to use an exclamation point in an email (or anywhere).

5. Avoid Rich Media Like Video and Flash

Most email clients cannot view rich media like Flash or video embeds by default. As for JavaScript and other dynamic scripts, even if a spam filter enables your email to go through, most email clients won't allow these scripts to function — so avoid using them altogether.

Instead, use an image of your video player (with a play button) that links to the rich media on a website page. If you want to communicate your video idea better, you can incorporate a GIF (with a link) and track the click-through rates thereafter. To clear your doubts about embedding videos in emails, read our guide on embedding videos in emails.

6. Avoid Attachments to Your Emails

Yes. The statement sounds vague, but including the attachments to your cold emails is never a good idea. An email with a short wall of text and all the first-hand information in the attachment could be left unnoticed. Also, the receivers consider the first emails with attachments spam or malicious.

This worsens the chances of getting your email to the spam folder. Upload the attachment to your website and link to the file location in your email using a practical call-to-action button. This will minimize the chance of being blocked by spam filters and decrease your email’s load time.

7. Don't Use Spam Trigger Words

One of the easiest ways to avoid spam filters is by carefully choosing the words you use in your email's subject line. A good rule of thumb is this: If it sounds like something a used car salesman would say, it's probably a spam trigger word. Think:

Free
Guarantee
No obligation, and so on.

Instead of using these trigger words, be creative, engaging, and informative—without giving too much away. Some better ideas for subject lines include:

“Hi [name], [question]?”
“Did you get what you were looking for?”
“You are not alone.”
“Feeling blue? Like puppies?”

8. Don't Forget to Use Spell Check

Spelling and grammar mistakes are the most embarrassing email offenses. According to a report by Grammarly, around 93% of the respondents made email typos and blunders. Of this, 63% committed embarrassing typos, while the recipients misunderstood 50%. To maintain good email etiquette, you must avoid typos. And, it‘s easy for little spelling mistakes to slip by — especially when you’re self-editing. Read this post to learn the most common spelling and grammar mistakes so you never make them again.

9. Avoid Jamming Your Email Copy with Keywords

Keyword-stuffing your emails means shoving as many keywords into your emails as possible. There‘s a reason Google gives a lower rank to web pages stuffed with keywords—because it harms user experience. To make it more likely folks will open your emails and not mark them as spam, write your emails for humans, not robots. Copywriting that makes people want to take action is both simple and compelling. Use casual language, colloquial expressions, and even personal anecdotes to make your writing sound more personable and relatable.

10. Avoid Using Too Many Images or Huge Images

Using one large image as your entire email, or too many images in general, tends to end up in recipients' spam folders. Most email recipients set their spam trigger criteria to filter heavily loaded images. To prevent long email load times, you’ll also want to make your image file sizes as small as possible without losing their visual integrity. Microsoft Outlook doesn't recognize background images, so you may want to avoid those and use a background color instead

11. Keep Your Email Lists Current and Clean

Even if your list is entirely built on valid opt-ins, you risk being branded a “spammer” if you don’t practice proper email hygiene. Why? Because internet service providers (ISPs) base complaint rates on active subscribers, not total subscribers.

Also, expired email addresses can become SPAM traps, meaning that even if you legitimately acquired emails, the abandoned addresses that haven't engaged in years may have morphed into spam traps. Hitting even just one spam trap can cause deliverability problems. Expired email addresses can also turn into unknown users (bounces).

The Importance of Email List Hygiene: Reducing Unknown Accounts to Protect Sender Reputation and Improve Deliverability

If you hit unknown accounts at a rate higher than 5%, then ISPs will see you as someone with lousy email hygiene. The result? They‘ll make it harder for your emails to reach people‘s inboxes, and your overall sender reputation will drop, leading to even more trouble reaching them.

Keeping your email lists current and clean will decrease the likelihood that people will flag your emails as spam. You can identify inactive subscribers and expired email addresses with metrics such as:

Opens
Clicks
Website activity

12. Re-Engage With Inactive Subscribers

Even if your email list is clean, the task is still half done. “Graymail” refers to emails people technically opt-in to receive but don‘t want. This leads them to become less active or inactive altogether. Although it’s not considered spam, sending graymail is problematic because it can hurt the deliverability of your email overall.

Tipped off by low engagement rates, ISPs, and inbox providers may deliver emails from known graymail senders straight to recipients‘ "junk" folders. Technically, the email gets sent (and can even appear to have been delivered), but it’s not necessarily seen.

Re-engagement Strategies: How to Win Back Inactive Subscribers and Strengthen Email Campaign Performance

Keep track of inactive and infrequently active subscribers and develop re-engagement campaigns for contacts who have stopped engaging with your messages. For example, you could set conditions such as the length of time since their last form submission, website visit, or email click, triggering the email when it’s been a while since they last engaged with you.

You can send them an exclusive offer or coupon in your workflow to get them excited about your company again. You can also ask for feedback by sending a quick survey to see what they want in your emails.

13. Make Use of Double Opt-Ins

Double opt-in confirmation is one of the best ways to reduce email bounce rates. Double opt-in means that after someone subscribes to your email list, you send them a follow-up email with a confirmation link, ensuring they want to receive your email communications. When you use double opt-in, your email lists will be much more qualified, and your subscribers will be much more engaged.

14. Ask Your Subscribers to Add You to Their Address Book

Spam filters are more aggressive than ever—so much so that sometimes, the emails people value and want to read still end up in their spam boxes. Ensure your emails get delivered by telling the subscriber’s email server that your email is safe enough to end up in their inbox. Thrivecart does an excellent job of making this happen. They specify why adding their email address is essential for the subscribers. Spam filters will back off when subscribers add you to their address book.

15. Include a Clear Unsubscribe Link and Physical Address in the Footer

There could be many reasons why your email subscribers want to opt out of your email list. It is always a good practice to allow people to unsubscribe to maintain list hygiene. In your marketing emails, you must include a way for folks to unsubscribe from your email list, either by simply sending a reply email or by clicking no more than one level deep to reach a page from which they can unsubscribe.

Your chosen method is entirely up to you if the information is clear and easy to locate. If you wish to evoke the subscriber’s interest, here are the best unsubscribe button ideas to save my subscribers. The most common place for these unsubscribe CTAs is in the footer of your email, so users tend to know to look for it there — which makes for a better user experience. Here‘s an example from one of HubSpot’s emails:

16. Use a Familiar Sender Name

Besides the subject line, the sender’s name is the second most crucial factor that gets your email read and opened. 45% of emails are opened because of the sender’s name. People are so inundated with SPAM that they hesitate to open emails from unfamiliar senders. Make sure recipients can recognize you as your sender by using your brand name. After establishing trust among the subscribers, create a personalization using the sender’s name.

Recipients are typically more likely to trust a personalized sender name and email address than a generic one. Use the original domain name instead of sending emails from Gmail, AOL, and Yahoo. I love this example from Userpilot that uses the sender’s name to create a sense of personalization. The email is sent on behalf of their content head, Emilia, using personal pronouns like ‘We’ and ‘I.’

17. Offer Recipients Both an HTML and a Plain Text Version of Your Emails

Plain text emails are simply emails void of any formatting, while HTML (HyperText Markup Language) emails use formatting that lets you design more beautiful emails with attractive visual components. By offering a plain text and HTML version of a single email, you‘re indicating your legitimacy to ISPs and making your emails more reader-friendly. Most email marketing tools will let you easily create plain-text versions within their email editor, so take those five extra minutes to make and optimize the plain-text version of your email. Also, ensure the HTML version is coded correctly: If your HTML has broken tags, the email provider and users might mark it as spam.

18. Allow People to View Your Email in a Web Browser

Even after every step is taken to ensure proper email design, an email client can still display an email poorly. Each client displays emails differently, and some clients have certain features that may render only partially in others. The way an email looks in Gmail might be different than how it looks in Yahoo or Outlook. Hence, it is crucial to include a link in every email so that the email can be viewed as a web page.

19. Include Alt Text in Your Email Images

Many email clients block images by default. When someone opens your email, the images will load if they click a button to show them or change their default settings. Adding alt text to your images helps recipients understand your message even if they can't see the pictures. This is especially bad if you use an image as a call-to-action. Without alt text, a “turned off” image will look like this: When you add alt text to the image, recipients will still know where to click to complete the action.

20. Keep Your Emails Short and Sweet

Too much copy is another red flag for spam filters. People generally like concise emails better. Everyone’s busy, and their inbox is complete, so why worsen things? Writing like a human is one of the best ways to keep things short and sweet. Writing your email like you were talking to someone in real life makes it feel much more approachable and relevant. If you must write a lengthier email, break it into multiple paragraphs. Giving visual breaks and composing the email with a clear introduction, middle, and conclusion will make it much easier for your reader.

21. Test Your Emails Before Sending Them

There are many email clients out there these days that email marketers have to consider when creating emails. We also must consider mobile users; 41% of people read email on their mobile devices. Since different email clients view emails differently, use the A/B testing technique to test your email copies. While it may be time-consuming to test your emails for all email clients, you'll want to test them for the ones your audience uses the most.

Optimizing Emails for Top Email Clients: Why Testing Across Platforms Matters for Campaign Success

According to Litmus' research of 1.06 billion emails opened, the top five email clients are:

Apple iPhone's Mail app (28% of users)
Gmail (16% of users)
Apple iPad's Mail app (11% of users)
Google Android's Mail app (9% of users)
Outlook (9% of users)

If your email marketing tool lets you go ahead and preview what your email looks like in different email clients and devices that are popular with your audience. You should also send out a test version of your email before sending out the real deal to ensure it works properly.

22. Get an Email Sender Accreditation From a Third Party

Sender accreditation is a third-party process of verifying email senders and requiring them to follow specific usage guidelines. This badge of trust adds your company email address to a trusted listing that ISPs refer to allow certain emails to bypass email filters.

23. Monitor the Reputation of Your Sender's IP Address

Your emails‘ deliverability depends mainly on your IP address’s reputation. If you‘re sending emails from an IP address with a poor reputation, your emails are far less likely to be successfully delivered to senders’ inboxs. DNSchecker.org lets you check on whether or not you are a blacklisted sender—something many unlucky email marketers aren't even aware of.

24. Stay Up-to-Date With Anti-Spam Laws, Spam Filters, and IPs Filter Technology

Email marketing constantly evolves, and staying in the know helps ensure you always follow best practices—and the law. Responsible and legitimate email marketers regularly read up on:

Email-sending laws
ISP behavior
Spam filter technology

If you need more information, consult your company’s legal department or a trusted lawyer to ensure you follow the law.

25. Make Emails Personal

Subscribers opt-in to receive your messages because they value your brand. Personalization makes subscribers feel:

Recognized
Boosting engagement
Conversions
Loyalty

Engage subscribers with tactics like:

Combining segmentation and personalization to align with where subscribers are in their journey, tailoring future messages based on their interests.
Dynamic content populates messages with product recommendations, exclusive offers, or relevant weather-based updates.
Engage subscribers with interactive elements, like polls or surveys, to make your emails more engaging and valuable.

26. Monitor Feedback Loops

Email feedback loops provide insights into how your campaigns perform post-send, helping you fine-tune your strategy. Review these metrics regularly with your team to quickly adapt to trends and address emerging deliverability challenges.

Start Buying Domains Now and Setup Your Email Infrastructure Today

Email deliverability refers to delivering emails to the recipient’s inbox rather than their spam folder or other tabs like "Promotions" or "Updates." A high email deliverability rate is fundamental for effective email marketing, as it determines how many of your sent emails reach your audience. As a rule of thumb, the higher your email deliverability rate, the better.

Email Deliverability vs. Deliverability Rate: Understanding the Difference and Why Inbox Placement Matters Most

For instance, an email deliverability rate of 90% means that out of 100 people you sent emails to, only 10 were in the spam folder. Email deliverability differs from email deliverability rate, which measures the percentage of emails reaching the intended destination. It’s possible to have a high email deliverability rate while the deliverability itself is low.

This happens when emails are reaching the wrong destination. In the example above, if you had a high email deliverability rate of 90% but only ten emails reached the inbox, with the rest going to the spam folder, you’d have a serious deliverability problem. What truly matters is getting as many emails as possible to the right place: the inbox.

What Affects Email Deliverability?

Several factors affect email deliverability, including:

Sender reputation
Domain authentication
Email engagement

Each factor has sub-factors that can help or hurt your email deliverability. For instance, a sender’s reputation is determined by your history of sending emails, and consistent and proper email practices can improve it.

At the same time, domain authentication helps establish your legitimacy as a sender so that receiving servers can identify you and trust that your emails are safe. Email engagement, on the other hand, is measured by how recipients interact with your emails and can be improved by creating relevant and targeted content that your audience cares about.

You send a fantastic email campaign, and can't wait to see the results. But when you open the reports, you're crushed to see that only a tiny fraction of your recipients ever opened your emails. What went wrong? While there are several potential explanations, one of the most common culprits is poor inbox delivery. Also known as "email deliverability," this metric measures the percentage of emails that reach their intended destination—inbox or spam folder. Recipients never see emails that end up in the spam folder or get filtered out and, therefore, can't achieve their goals, whether boosting sales, generating leads, or improving audience engagement. In this article, we'll cover what affects email deliverability to help you get your emails back on track so they land in recipients' inboxes, boosting engagement, conversions, and the overall success of your email campaigns.

Getting your emails to the inbox requires a solid email infrastructure. Inframail's email infrastructure helps you build a healthy sender reputation so your emails get the attention they deserve.

What is Email Deliverability and Its Importance

Email deliverability is the rate at which your email makes it into recipient inboxes. An email deliverability rate can be lower when an email bounces or gets automatically filtered into a spam folder. Imagine you send mail to a friend with a missing sender name. The post could end up in the trash because of the unknown sender. Similarly, emails may get delivered to the recipient’s email address but in a spam or marketing folder.

‘Email deliverability’ may often be confused with ‘email delivery.’ While both terms refer to email delivery, there is a striking difference between them.

Email Delivery vs. Email Deliverability

Email delivery measures the number of emails delivered successfully, regardless of the folder. It tells if the recipient’s mail server has accepted the email file and offered it to the receiver. It calculates the percentage of emails that didn’t bounce out of the sent emails.

Email deliverability is akin to the number of emails that reach the right destination. Also known as inbox placement, it calculates the percentage of emails that get delivered to the priority inbox. For example, the deliverability rate of 100 emails, out of which 33 were in the spam folder, is 66%.

Key Differences Between Email Delivery and Email Deliverability: Causes, Challenges, and How to Address Them

A straightforward summary of this email delivery vs. email deliverability comparison is as follows:

Email delivery = How many emails were delivered?

Email deliverability = How many emails were delivered to the recipient’s inbox?

Delivery issues may be due to the following:

Faulty email addresses
Problems with your infrastructure
Too much negative feedback on the email address

Deliverability issues arise due to outdated sending and permission practices, violating a law, or receiving too many spam labels by the receivers.

Why Does Email Deliverability Matter So Much?

Email deliverability is crucial for higher ROI. For every $1 spent, email gives an ROI of around $36. Even if the email delivery rate is around 97% for the 1,000 emails sent, there are still 30 emails that bounce back. Now, consider the open rates. The open rates might oscillate around 30%-40%.

One primary reason for low open rates could be email deliverability. Emails in the spam or promotional folders have lower open rates because they are often overlooked. For email marketers, getting higher open rates is imperative. To ensure that, it is essential that every email that you send ends up in the inbox.

What Affects Email Deliverability?

Sender Reputation: The Most Important Factor That Affects Email Deliverability

Email servers assign a sender score to you based on the quality of your past email campaigns. If many recipients mark your emails as spam, or if your messages bounce back from:

Unvalidated email addresses
Your sender’s reputation declines
Undermining your email deliverability

Besides sender reputation, email deliverability also relies on the following:

Domain Reputation

It’s the reputation your domain earns from an email service provider based on how recipients engage with your emails. If more contacts open and respond to your emails, you earn a positive domain reputation, and if more prospects tag your email as spam, your domain reputation declines.  

IP Address Reputation

It measures how well an IP address behaves. If an IP address sends genuine, spam-free emails, it earns a positive IP reputation, and if it’s associated with malware and bulk spam mail, it gets a negative IP reputation.

Email Authentication: Proving You're Not a Spammy Robot

Email authentication is setting up authentication protocols to ensure the email service provider that you’re the one sending the outreach emails and they can be trusted.

The three major authentication protocols are as follows:  

SPF (Sender Policy Framework)

The Sender Policy Framework protects you and your recipients from spam and spoofing. It enables you to add a list of senders authorized to send email from your domain. For instance, using an SPF record, you can use separate email APIs or software tools for your marketing and sales emails and add both services as approved senders.

This lets your contacts know that the messages are authentic and trustworthy.

DKIM (DomainKeys Identified Mail)

DKIM uses digital signatures and encryption keys to validate your emails and prevent recipients from replying to illegitimate messages.  

DMARC (Domain-based Message Authentication Reporting & Conformance)

DMARC adds an extra layer of security to your emails – an alignment test. It also lets you warn recipient servers about a failed email test so that they can discard or quarantine a suspicious email.

Email List Quality: The More You Know

Maintaining a high-quality contact list is paramount in ensuring a smooth and hassle-free email delivery. You can retain your active subscribers by gathering a targeted email list and sending personalized campaigns relevant to users on that list. At the same time, you could win back my inactive subscribers through various re-engagement campaigns. If people need to be more actively engaging with your campaign, reduce the emails you send them or scrub my list.

This is because many inactive subscribers on my list can impact my delivery. If my subscribers have yet to respond after a reconfirmation campaign, consider deleting those inactive IDs. While it could be painful to trim down my hard-earned list, in the long run, you will thank yourself because the better the list quality, the better the engagement rate.

Email Volume and Frequency: Don’t Go Overboard

Spammers usually send blasts of emails to recipients from a new domain before the recipient mailbox provider can identify and block them. When you start your outreach campaign from a fresh domain, sending bulk emails can trigger a spam filter. Instead, start by sending a small volume of messages at regular intervals to build up your reputation.

Maintain the cadence during your initial cold emailing days and gradually increase the number of emails. Besides email volume, the frequency of sending them also affects deliverability. Email frequency is not fixed and evolves as you build your sender reputation. Start with a low frequency of emails and then increase it depending on prospect engagement.

Email Subject Line and Content: Make It Appealing and Legit

Most recipients will open your email depending on its subject line. A misleading or clickbait-y subject line can turn off readers and trigger them to mark your messages as spam. An email service provider like Gmail can even identify spammy keywords in your subject line and send your emails to spam. Besides your subject line, your email’s content must also be free of spammy words to get past most spam filters.

The content of your marketing email is a critical factor in determining its deliverability. This is mainly because spam filters of popular email service providers analyze the content, headers, message texts, and attachments to identify and block potentially malicious content. Sadly, some reports state that legitimate emails end up in spam folders from:

Pharmaceutical companies
Dating sites
Mortgages

Evolution of Spam Filters: From Basic Pattern Matching to Advanced Collaborative Filtering and Their Potential Drawbacks

The first few generations of spam filters were relatively limited and straightforward. For example, they could match and identify only specific patterns of emails. Recent filtering techniques have introduced more advanced collaborative filters whereby multiple services and sites can contribute spam reports to a centralized service.

One problem with this collaborative filter technology is that if a filter identifies a particular message as spam and submits the report to a centralized service, all the other service providers take up the same information without asking questions.

Email Engagement Metrics: Keep Track of Performance

You can assess the success of your email campaign using these key metrics:  

Spam Complaint Rate

The number of email recipients marked as spam out of all your outbound messages. The industry-acceptable spam rate is 0.1%. Anything above that will lower your deliverability.  

Bounce Rate

The percentage of your emails that bounce back or are rejected by recipients. This usually happens when:

You email a risky contact
Who could be an invalid
A spam trap
Someone with a strong filter on incoming emails. (You’ll want this rate below 2.8% for cold emails.)

Response Rate

It’s a metric of the number of emails that receive a response out of the total emails sent. A reasonable response rate is around 10%, but 5% might be a reasonable target in some segments.  

Inbox Placement Rate

The percentage of outbound emails that reach a prospect’s primary inbox out of your outgoing emails. (meaning they didn’t land in spam or junk folders). You’ll want this to be above 90%.  

Open Rate

It’s the percentage of emails your recipients open. Although this isn’t as accurate as it used to be, generally, you’ll want this rate above 50% and need to watch for declines as an early signal of deliverability issues.

Unsubscribe and Double Opt-in Provisions: Give Them an Out

Only some of your contacts are interested in your emails, and they prefer a way out to stop receiving your emails. Including an option to unsubscribe gives your prospects a chance to stop receiving your emails. If you don’t do so, uninterested contacts might be more likely to report your emails as spam to stop receiving them and dent my deliverability.

Likewise, for prospects who’ve subscribed to your email list, adding another opt-in link to confirm their subscription ensures that they’re genuinely interested and not likely to flag your emails. (this is called double opt-in).

Spam Trap Issues: Avoid Getting Caught

Spam traps are fraud management tools used by internet service providers, anti-spam organizations, etc., to identify and block emails from spammers. Spam traps often look like regular email addresses, but they cannot be used for communication as they do not belong to any person or organization.

Spam traps can cause your domain or IP address to be denied, affecting your email deliverability rates and sender reputation. You may not be a spammer, but it is essential to understand the potential dangers hidden in spam traps and avoid adding them to your contact list.

Email Bounces: Don't Let Them Get Out of Control

Email bounces occur when messages are not delivered to the recipient's inbox. Email service providers want their customers to see that brands follow good practices to acquire subscribers, so they opt for two different methods.

ESP brands send too many emails to IDs that don't exist. When emails are delivered to non-existing IDs, those emails experience hard bounces. In such a case, email service providers block those IDs to ensure that non-future emails will be delivered to them. Keep in mind that if you experience more than 2% of hard bounces, it will affect your deliverability.

Mobile-friendly Designs: Adapt to Your Audience

Gone are the days when users sat in front of their computers to check their emails. The 21st century marked the smartphone revolution. Users prefer to check their emails on portable devices such as smartphones or tablets. Research has indicated that over 43% of emails are opened through a mobile device. The rate is so high that it is common for companies to make a mobile-friendly design while sending emails.

Best Practices for Creating Mobile-Friendly Emails to Boost Deliverability and Subscriber Engagement

Imagine that your marketing emails must load correctly on a mobile device. In this scenario, there is a high chance it will turn off your loyal subscribers, eventually losing them to your competitors. To improve your email deliverability rates, you should adopt design templates that are easier to view on mobile devices.

Some techniques to adopt for producing a mobile-friendly design include:  Use single-column templates  The width of your email template should be 600 pixels  Provide a clear CTA button  Use large fonts  Display small images, etc.  Use URL shorteners.

Email Infrastructure: It’s About More Than Just Content

Email deliverability largely depends on the software and hardware systems despite everything being on the cloud. The email system works much like a real-life postal service system; after you write a letter and dispatch it for delivery, the postal services, the people who sort the letters, and the delivery persons deliver the posts to the receiver’s doorstep.

In the same way, email deliverability depends on three hardware and software structures: mail servers, agents, and IP addresses. If you have a high email volume, you need a dedicated IP that provides a robust and seamless email infrastructure.

Levels of Engagement: Pay Attention to Feedback

Email service providers pay attention to positive and negative feedback on an email. The input is usually based on the time spent reading the mail, CTR, and open rates. Research has shown that positive engagement is an essential factor affecting deliverability.

Thus, senders must manage their inactive subscribers by reducing the emails sent to them and eventually deleting them from the list. Sending more personalized and segmented email campaigns can boost the engagement rate of the mail, which also positively impacts deliverability.

26 Ways to Improve Email Deliverability Rate

1. Don't Buy or Rent Email Lists

Resist the urge to buy or rent email lists. Yes, you can legally rent and purchase lists of people who have agreed to email communications—but it's never a good idea. Not only is it a dirty email marketing tactic that goes against the Terms of Service for your email service provider, but these people don‘t know you—and it’s likely they won't even want your emails. In other words, there‘s a good chance they’ll mark you as spam. Plus, be honest… high-quality email addresses are never for sale.

2. Don't Email People Who Have Bounced Repeatedly

Bounce rates are one of the key factors internet service providers (ISPs) use to determine an email sender‘s reputation, so having too many hard bounces can cause them to stop allowing your emails in folks’ inboxes. Hard bounces result from non-existent email addresses, domains, and typos in the recipient’s email address. Re-attempts to send duplicate emails will further aggravate the bounce rates, which is a red flag for ISPs.

3. Avoid All Caps in Your Emails

Using caps in email subject lines lowers the response rate by 30%. It looks like you are shouting at your audience, making your email less readable and disinteresting. It's annoying and can seem spammy. Instead of using disruptive tactics like all caps to get people's attention, try personalizing your emails and using catchy and delightful language. (Read this blog post on how to write compelling emails for more tips.)

4. Avoid Excessive Punctuation

Even the smallest of symbols can drastically change the destiny of your email. Using too many exclamation points seems unprofessional and dominating. You don’t need any fillers to get your emails noticed. And when 69% of email recipients report email as spam based solely on the subject line, you'll want to avoid triggers like this as much as possible. Plus, asking for punctuation to do a word’s job can dilute your message. Use this flowchart as a gut check when tempted to use an exclamation point in an email (or anywhere).

5. Avoid Rich Media Like Video and Flash

Most email clients cannot view rich media like Flash or video embeds by default. As for JavaScript and other dynamic scripts, even if a spam filter enables your email to go through, most email clients won't allow these scripts to function — so avoid using them altogether.

Instead, use an image of your video player (with a play button) that links to the rich media on a website page. If you want to communicate your video idea better, you can incorporate a GIF (with a link) and track the click-through rates thereafter. To clear your doubts about embedding videos in emails, read our guide on embedding videos in emails.

6. Avoid Attachments to Your Emails

Yes. The statement sounds vague, but including the attachments to your cold emails is never a good idea. An email with a short wall of text and all the first-hand information in the attachment could be left unnoticed. Also, the receivers consider the first emails with attachments spam or malicious.

This worsens the chances of getting your email to the spam folder. Upload the attachment to your website and link to the file location in your email using a practical call-to-action button. This will minimize the chance of being blocked by spam filters and decrease your email’s load time.

7. Don't Use Spam Trigger Words

One of the easiest ways to avoid spam filters is by carefully choosing the words you use in your email's subject line. A good rule of thumb is this: If it sounds like something a used car salesman would say, it's probably a spam trigger word. Think:

Free
Guarantee
No obligation, and so on.

Instead of using these trigger words, be creative, engaging, and informative—without giving too much away. Some better ideas for subject lines include:

“Hi [name], [question]?”
“Did you get what you were looking for?”
“You are not alone.”
“Feeling blue? Like puppies?”

8. Don't Forget to Use Spell Check

Spelling and grammar mistakes are the most embarrassing email offenses. According to a report by Grammarly, around 93% of the respondents made email typos and blunders. Of this, 63% committed embarrassing typos, while the recipients misunderstood 50%. To maintain good email etiquette, you must avoid typos. And, it‘s easy for little spelling mistakes to slip by — especially when you’re self-editing. Read this post to learn the most common spelling and grammar mistakes so you never make them again.

9. Avoid Jamming Your Email Copy with Keywords

Keyword-stuffing your emails means shoving as many keywords into your emails as possible. There‘s a reason Google gives a lower rank to web pages stuffed with keywords—because it harms user experience. To make it more likely folks will open your emails and not mark them as spam, write your emails for humans, not robots. Copywriting that makes people want to take action is both simple and compelling. Use casual language, colloquial expressions, and even personal anecdotes to make your writing sound more personable and relatable.

10. Avoid Using Too Many Images or Huge Images

Using one large image as your entire email, or too many images in general, tends to end up in recipients' spam folders. Most email recipients set their spam trigger criteria to filter heavily loaded images. To prevent long email load times, you’ll also want to make your image file sizes as small as possible without losing their visual integrity. Microsoft Outlook doesn't recognize background images, so you may want to avoid those and use a background color instead

11. Keep Your Email Lists Current and Clean

Even if your list is entirely built on valid opt-ins, you risk being branded a “spammer” if you don’t practice proper email hygiene. Why? Because internet service providers (ISPs) base complaint rates on active subscribers, not total subscribers.

Also, expired email addresses can become SPAM traps, meaning that even if you legitimately acquired emails, the abandoned addresses that haven't engaged in years may have morphed into spam traps. Hitting even just one spam trap can cause deliverability problems. Expired email addresses can also turn into unknown users (bounces).

The Importance of Email List Hygiene: Reducing Unknown Accounts to Protect Sender Reputation and Improve Deliverability

If you hit unknown accounts at a rate higher than 5%, then ISPs will see you as someone with lousy email hygiene. The result? They‘ll make it harder for your emails to reach people‘s inboxes, and your overall sender reputation will drop, leading to even more trouble reaching them.

Keeping your email lists current and clean will decrease the likelihood that people will flag your emails as spam. You can identify inactive subscribers and expired email addresses with metrics such as:

Opens
Clicks
Website activity

12. Re-Engage With Inactive Subscribers

Even if your email list is clean, the task is still half done. “Graymail” refers to emails people technically opt-in to receive but don‘t want. This leads them to become less active or inactive altogether. Although it’s not considered spam, sending graymail is problematic because it can hurt the deliverability of your email overall.

Tipped off by low engagement rates, ISPs, and inbox providers may deliver emails from known graymail senders straight to recipients‘ "junk" folders. Technically, the email gets sent (and can even appear to have been delivered), but it’s not necessarily seen.

Re-engagement Strategies: How to Win Back Inactive Subscribers and Strengthen Email Campaign Performance

Keep track of inactive and infrequently active subscribers and develop re-engagement campaigns for contacts who have stopped engaging with your messages. For example, you could set conditions such as the length of time since their last form submission, website visit, or email click, triggering the email when it’s been a while since they last engaged with you.

You can send them an exclusive offer or coupon in your workflow to get them excited about your company again. You can also ask for feedback by sending a quick survey to see what they want in your emails.

13. Make Use of Double Opt-Ins

Double opt-in confirmation is one of the best ways to reduce email bounce rates. Double opt-in means that after someone subscribes to your email list, you send them a follow-up email with a confirmation link, ensuring they want to receive your email communications. When you use double opt-in, your email lists will be much more qualified, and your subscribers will be much more engaged.

14. Ask Your Subscribers to Add You to Their Address Book

Spam filters are more aggressive than ever—so much so that sometimes, the emails people value and want to read still end up in their spam boxes. Ensure your emails get delivered by telling the subscriber’s email server that your email is safe enough to end up in their inbox. Thrivecart does an excellent job of making this happen. They specify why adding their email address is essential for the subscribers. Spam filters will back off when subscribers add you to their address book.

15. Include a Clear Unsubscribe Link and Physical Address in the Footer

There could be many reasons why your email subscribers want to opt out of your email list. It is always a good practice to allow people to unsubscribe to maintain list hygiene. In your marketing emails, you must include a way for folks to unsubscribe from your email list, either by simply sending a reply email or by clicking no more than one level deep to reach a page from which they can unsubscribe.

Your chosen method is entirely up to you if the information is clear and easy to locate. If you wish to evoke the subscriber’s interest, here are the best unsubscribe button ideas to save my subscribers. The most common place for these unsubscribe CTAs is in the footer of your email, so users tend to know to look for it there — which makes for a better user experience. Here‘s an example from one of HubSpot’s emails:

16. Use a Familiar Sender Name

Besides the subject line, the sender’s name is the second most crucial factor that gets your email read and opened. 45% of emails are opened because of the sender’s name. People are so inundated with SPAM that they hesitate to open emails from unfamiliar senders. Make sure recipients can recognize you as your sender by using your brand name. After establishing trust among the subscribers, create a personalization using the sender’s name.

Recipients are typically more likely to trust a personalized sender name and email address than a generic one. Use the original domain name instead of sending emails from Gmail, AOL, and Yahoo. I love this example from Userpilot that uses the sender’s name to create a sense of personalization. The email is sent on behalf of their content head, Emilia, using personal pronouns like ‘We’ and ‘I.’

17. Offer Recipients Both an HTML and a Plain Text Version of Your Emails

Plain text emails are simply emails void of any formatting, while HTML (HyperText Markup Language) emails use formatting that lets you design more beautiful emails with attractive visual components. By offering a plain text and HTML version of a single email, you‘re indicating your legitimacy to ISPs and making your emails more reader-friendly. Most email marketing tools will let you easily create plain-text versions within their email editor, so take those five extra minutes to make and optimize the plain-text version of your email. Also, ensure the HTML version is coded correctly: If your HTML has broken tags, the email provider and users might mark it as spam.

18. Allow People to View Your Email in a Web Browser

Even after every step is taken to ensure proper email design, an email client can still display an email poorly. Each client displays emails differently, and some clients have certain features that may render only partially in others. The way an email looks in Gmail might be different than how it looks in Yahoo or Outlook. Hence, it is crucial to include a link in every email so that the email can be viewed as a web page.

19. Include Alt Text in Your Email Images

Many email clients block images by default. When someone opens your email, the images will load if they click a button to show them or change their default settings. Adding alt text to your images helps recipients understand your message even if they can't see the pictures. This is especially bad if you use an image as a call-to-action. Without alt text, a “turned off” image will look like this: When you add alt text to the image, recipients will still know where to click to complete the action.

20. Keep Your Emails Short and Sweet

Too much copy is another red flag for spam filters. People generally like concise emails better. Everyone’s busy, and their inbox is complete, so why worsen things? Writing like a human is one of the best ways to keep things short and sweet. Writing your email like you were talking to someone in real life makes it feel much more approachable and relevant. If you must write a lengthier email, break it into multiple paragraphs. Giving visual breaks and composing the email with a clear introduction, middle, and conclusion will make it much easier for your reader.

21. Test Your Emails Before Sending Them

There are many email clients out there these days that email marketers have to consider when creating emails. We also must consider mobile users; 41% of people read email on their mobile devices. Since different email clients view emails differently, use the A/B testing technique to test your email copies. While it may be time-consuming to test your emails for all email clients, you'll want to test them for the ones your audience uses the most.

Optimizing Emails for Top Email Clients: Why Testing Across Platforms Matters for Campaign Success

According to Litmus' research of 1.06 billion emails opened, the top five email clients are:

Apple iPhone's Mail app (28% of users)
Gmail (16% of users)
Apple iPad's Mail app (11% of users)
Google Android's Mail app (9% of users)
Outlook (9% of users)

If your email marketing tool lets you go ahead and preview what your email looks like in different email clients and devices that are popular with your audience. You should also send out a test version of your email before sending out the real deal to ensure it works properly.

22. Get an Email Sender Accreditation From a Third Party

Sender accreditation is a third-party process of verifying email senders and requiring them to follow specific usage guidelines. This badge of trust adds your company email address to a trusted listing that ISPs refer to allow certain emails to bypass email filters.

23. Monitor the Reputation of Your Sender's IP Address

Your emails‘ deliverability depends mainly on your IP address’s reputation. If you‘re sending emails from an IP address with a poor reputation, your emails are far less likely to be successfully delivered to senders’ inboxs. DNSchecker.org lets you check on whether or not you are a blacklisted sender—something many unlucky email marketers aren't even aware of.

24. Stay Up-to-Date With Anti-Spam Laws, Spam Filters, and IPs Filter Technology

Email marketing constantly evolves, and staying in the know helps ensure you always follow best practices—and the law. Responsible and legitimate email marketers regularly read up on:

Email-sending laws
ISP behavior
Spam filter technology

If you need more information, consult your company’s legal department or a trusted lawyer to ensure you follow the law.

25. Make Emails Personal

Subscribers opt-in to receive your messages because they value your brand. Personalization makes subscribers feel:

Recognized
Boosting engagement
Conversions
Loyalty

Engage subscribers with tactics like:

Combining segmentation and personalization to align with where subscribers are in their journey, tailoring future messages based on their interests.
Dynamic content populates messages with product recommendations, exclusive offers, or relevant weather-based updates.
Engage subscribers with interactive elements, like polls or surveys, to make your emails more engaging and valuable.

26. Monitor Feedback Loops

Email feedback loops provide insights into how your campaigns perform post-send, helping you fine-tune your strategy. Review these metrics regularly with your team to quickly adapt to trends and address emerging deliverability challenges.

Start Buying Domains Now and Setup Your Email Infrastructure Today

Email deliverability refers to delivering emails to the recipient’s inbox rather than their spam folder or other tabs like "Promotions" or "Updates." A high email deliverability rate is fundamental for effective email marketing, as it determines how many of your sent emails reach your audience. As a rule of thumb, the higher your email deliverability rate, the better.

Email Deliverability vs. Deliverability Rate: Understanding the Difference and Why Inbox Placement Matters Most

For instance, an email deliverability rate of 90% means that out of 100 people you sent emails to, only 10 were in the spam folder. Email deliverability differs from email deliverability rate, which measures the percentage of emails reaching the intended destination. It’s possible to have a high email deliverability rate while the deliverability itself is low.

This happens when emails are reaching the wrong destination. In the example above, if you had a high email deliverability rate of 90% but only ten emails reached the inbox, with the rest going to the spam folder, you’d have a serious deliverability problem. What truly matters is getting as many emails as possible to the right place: the inbox.

What Affects Email Deliverability?

Several factors affect email deliverability, including:

Sender reputation
Domain authentication
Email engagement

Each factor has sub-factors that can help or hurt your email deliverability. For instance, a sender’s reputation is determined by your history of sending emails, and consistent and proper email practices can improve it.

At the same time, domain authentication helps establish your legitimacy as a sender so that receiving servers can identify you and trust that your emails are safe. Email engagement, on the other hand, is measured by how recipients interact with your emails and can be improved by creating relevant and targeted content that your audience cares about.

What Affects Email Deliverability & 26 Tips for Better Campaigns

What Affects Email Deliverability & 26 Tips for Better Campaigns

What Affects Email Deliverability & 26 Tips for Better Campaigns

Table of Contents

What is Email Deliverability and Its Importance

Email Delivery vs. Email Deliverability

Key Differences Between Email Delivery and Email Deliverability: Causes, Challenges, and How to Address Them

Why Does Email Deliverability Matter So Much?

Related Reading

What Affects Email Deliverability?

Sender Reputation: The Most Important Factor That Affects Email Deliverability

Domain Reputation

IP Address Reputation

Email Authentication: Proving You're Not a Spammy Robot

SPF (Sender Policy Framework)

DKIM (DomainKeys Identified Mail)

DMARC (Domain-based Message Authentication Reporting & Conformance)

Email List Quality: The More You Know

Email Volume and Frequency: Don’t Go Overboard

Email Subject Line and Content: Make It Appealing and Legit

Evolution of Spam Filters: From Basic Pattern Matching to Advanced Collaborative Filtering and Their Potential Drawbacks

Email Engagement Metrics: Keep Track of Performance

Spam Complaint Rate

Bounce Rate

Response Rate

Inbox Placement Rate

Open Rate

Unsubscribe and Double Opt-in Provisions: Give Them an Out

Spam Trap Issues: Avoid Getting Caught

Email Bounces: Don't Let Them Get Out of Control

Mobile-friendly Designs: Adapt to Your Audience

Best Practices for Creating Mobile-Friendly Emails to Boost Deliverability and Subscriber Engagement

Email Infrastructure: It’s About More Than Just Content

Levels of Engagement: Pay Attention to Feedback

Related Reading

26 Ways to Improve Email Deliverability Rate

1. Don't Buy or Rent Email Lists

2. Don't Email People Who Have Bounced Repeatedly

3. Avoid All Caps in Your Emails

4. Avoid Excessive Punctuation

5. Avoid Rich Media Like Video and Flash

6. Avoid Attachments to Your Emails

7. Don't Use Spam Trigger Words

8. Don't Forget to Use Spell Check

9. Avoid Jamming Your Email Copy with Keywords

10. Avoid Using Too Many Images or Huge Images

11. Keep Your Email Lists Current and Clean

The Importance of Email List Hygiene: Reducing Unknown Accounts to Protect Sender Reputation and Improve Deliverability

12. Re-Engage With Inactive Subscribers

Re-engagement Strategies: How to Win Back Inactive Subscribers and Strengthen Email Campaign Performance

13. Make Use of Double Opt-Ins

14. Ask Your Subscribers to Add You to Their Address Book

15. Include a Clear Unsubscribe Link and Physical Address in the Footer

16. Use a Familiar Sender Name

17. Offer Recipients Both an HTML and a Plain Text Version of Your Emails

18. Allow People to View Your Email in a Web Browser

19. Include Alt Text in Your Email Images

20. Keep Your Emails Short and Sweet

21. Test Your Emails Before Sending Them

Optimizing Emails for Top Email Clients: Why Testing Across Platforms Matters for Campaign Success

22. Get an Email Sender Accreditation From a Third Party

23. Monitor the Reputation of Your Sender's IP Address

24. Stay Up-to-Date With Anti-Spam Laws, Spam Filters, and IPs Filter Technology

25. Make Emails Personal

26. Monitor Feedback Loops

Related Reading

Start Buying Domains Now and Setup Your Email Infrastructure Today

Email Deliverability vs. Deliverability Rate: Understanding the Difference and Why Inbox Placement Matters Most

What Affects Email Deliverability?

Table of Contents

What is Email Deliverability and Its Importance

Email Delivery vs. Email Deliverability

Key Differences Between Email Delivery and Email Deliverability: Causes, Challenges, and How to Address Them

Why Does Email Deliverability Matter So Much?

Related Reading

What Affects Email Deliverability?

Sender Reputation: The Most Important Factor That Affects Email Deliverability

Domain Reputation

IP Address Reputation

Email Authentication: Proving You're Not a Spammy Robot