Imagine for a moment that you own a small bakery. You create an email marketing campaign to promote your delicious new brownie flavor. But when you check back days later, no one has even opened your email. What went wrong? Why are my emails going to spam? If you’ve ever been in a similar situation, you know how frustrating it can be. Not only do emails that wind up in the spam folder hurt your ego, but they can also severely damage your business. Not only do you miss out on valuable engagement from your target audience, but emails that go to spam hurt your sender reputation, which can impact future campaigns. In this article, we’ll discuss why emails go to spam and how you can improve inbox delivery.  

By the end, you’ll understand why your emails are being marked as spam and learn effective strategies to ensure your emails reach the inbox. 

Inframail's email infrastructure services can help you achieve these objectives. Our tools monitor the health of your email programs, so you can identify issues before they impact deliverability.

Table of Contents

• What’s a Spam Filter, and How Does It Work?

• Why Are My Emails Going to Spam?

• 5 Ways to Avoid Landing in the Spam Box

• Start Buying Domains Now and Setup Your Email Infrastructure Today

What’s a Spam Filter, and How Does It Work?

Spam filters identify unsolicited or dangerous emails so providers can stop those messages from reaching the inbox. Spam is unsolicited and often harmful or irrelevant messages. For example, if you send an email to a customer and they don’t recognize your name, business, or brand, there’s a good chance your email will go to spam. That’s if they even open it at all. 

How Spam Filters Work: Scoring, Fingerprinting, and Machine Learning Explained

Spam filters use various techniques to detect and block these unwanted messages. 

Some Spam Filters Rely on Scoring Mechanisms

If an email’s spam score exceeds a certain threshold, the filter will mark it as spam. 

Others Use Fingerprinting

This approach involves spam filters, which keep a collection of known spam messages and then calculate how likely an incoming email has a similar intent. Advanced filtering mechanisms also use machine learning to stay on top of spam. It’s crucial to know that no two spam filters look alike. 

Gmail’s approach to spam scoring will differ from how Yahoo! Mail filters spam, so there’s a chance that your email might make it to the inbox with one provider and land in spam with the other. 

All Spam Filters Have One Thing in Common

They’re set up to ensure the inbox remains clean and safe, providing an excellent email recipient experience. So when an email goes to spam, you’ve done something that caused inbox providers to believe your email is unsolicited or even dangerous, or your email is simply replicating current trends in actual spam, whether: 

• Personal messages

• Your brand’s newsletter

• Transactional email

How Can I Stop My Emails From Going to Spam?

It’s not easy to get emails out of the spam folder. If you send a follow-up email to a recipient who previously opened your messages, there’s a chance it will go to their inbox. But there’s also a chance it will go to spam again. 

Even worse, the more you improve your email and resend it to the same recipient, the more likely it is to remain in the spam folder. The best way to deal with spam is to prevent it in the first place.

 Related Reading

• Email Deliverability Rate
• Email Monitoring
• Email Deliverability Issues
• Email Quality Score
• Bounce Rate in Email Marketing
• How To Avoid Email Going To Spam
• Why Do Emails Bounce
• SPF or DKIM
• How To Check If Your Emails Are Going To Spam

Why Are My Emails Going to Spam?

1. Your Email Isn’t Properly Authenticated

Spammers can easily impersonate your brand. To stop this from happening, you can use email authentication standards. Authentication helps inbox providers identify which emails are legitimate and which are spam. When emails lack authentication, spam filters raise red flags. Missing or improperly set up authentication is one of the most common reasons legitimate emails get thrown into the spam folder. 

So, when you’re troubleshooting spam issues, start here. Check if you set up SPF (Sender Policy Framework) correctly to provide a public list of sending IPs approved to send email from your domain. 

Mastering Email Authentication: SPF, DKIM, and DMARC for Better Deliverability and Security

Here’s our complete guide to SPF. 

• Are your emails signed using DKIM (DomainKeys Identified Mail), an email security standard designed to ensure messages aren’t altered in transit? Our DKIM guide can give you more details about how it works to secure your email. 

• Did you set up DMARC correctly? DMARC allows you to tell inbox providers to quarantine or reject emails not sent from a trusted source. If you don’t have it set up, scammers might send spam using your domain and hurt your domain reputation (and thus your deliverability). 

If you set up DMARC but it’s not configured correctly, you might accidentally send my legitimate email to the spam folder. Learn to set up DMARC with our ultimate DMARC guide to avoid these mistakes.

2. Your Sending IP Has a Bad Reputation

The IP address you use to send your emails is crucial for deliverability. People build up a reputation over time (a good one if you behave like a good human, a bad one if you’re being a jerk), and each IP address has a history that mailbox providers keep track of. For example, a track record of low spam complaints and bounce rates makes your sending IP more trustworthy, while many complaints will dent your IP’s credibility. 

When sending email via a shared IP, your IP reputation isn’t just built on your sending activity and the combined sending habits of all senders on your IP. If you’re sharing your IP with spammers, your delivery will suffer. That doesn’t mean a shared IP is terrible, though: If you’re associated with good senders, that can help boost your deliverability. Your email landed in the Spam folder? Let’s see if a lousy IP rep might be the culprit: Find out how good (or bad) your IP reputation is. 

How to Check and Improve Your Sending IP Reputation for Email Deliverability

Here’s a detailed guide for finding your sending IP and what tools to use to check your IP reputation in just a few steps. 

• Check if your IP is on a block list. MultiRBL is a popular service for quickly checking block listings. 

• Are you seeing IP reputation issues? Reach out to your email service provider (ESP) to see if they can provide any more insights on what might be causing it and whether they’re already working on a fix. If you’re working with a great ESP that only allows legitimate senders to use their platform (and ruthlessly weeds out spammers), IP reputation issues happen rarely or never. 

3. Your Domain Has a Bad Reputation 

Like your sending IP, your domain has a history, too—and spam filters are putting more and more weight on domain reputation when scoring your emails. That makes sense: You might be changing email service providers or will use different providers for different types of emails, all of which will use different IPs to send your emails. Your domain is likely the same across providers, so looking at your domain reputation is a clever way to judge your trustworthiness as a sender. 

To determine whether a low sending domain reputation could be the reason for a spam folder placement:

• Check your domain reputation for senders who share the data with you. Gmail’s Postmaster tools, for example, will provide you with a detailed domain reputation score. 

• See if your domain is on blocklists, as those significantly impact your reputation. MXToolBox or multiRBL.valli.org are two popular services for checking multiple blocklists at once. 

4. Your Recipients Marked Your Emails as Spam

If recipients mark an email as spam, that’s probably the most straightforward feedback mailbox providers can consider when judging your emails. So, it’s inevitable that users’ spam reports directly impact your deliverability. A high rate of users hitting the spam button will affect your reputation as a sender and cause future emails to land in the spam folder. 

Identifying and Addressing User Complaints to Prevent Emails from Landing in Spam

Here are a few things you can do to determine if user complaints might be why your emails land in spam: 

• Find out how many recipients are marking your emails as spam. If you’re using Google’s Postmaster tools, you can easily see the spam rate (the percentage of emails marked as spam by users vs emails sent to the inbox for active users). 

• Register for all available feedback loops, a service provided by some mailbox providers that share insights about spam complaints generated by your campaigns. (If you’re using Postmark, we take care of that for you and provide spam complaint information right within Postmark.) 

If you see a spike in complaints, it’s time to investigate: 

• Did a specific campaign cause them? 

• Who are the folks complaining? 

• Did they all come from the same acquisition source? 

Stop sending emails to people who marked your emails as spam. If you continue to send to these folks, that could tank your reputation even further. 

5. You Don’t Keep a Clean Email List

Spammers and phishers typically don’t have a record of great list-keeping. They shamelessly scrape (or steal) email addresses from somewhere, don’t care about invalid email addresses or bounces, and don’t care about engagement as long as a few clueless victims fall for their traps. If inbox providers assume similar questionable list-building techniques for your brand, they’ll also place you into the spam folder. That’s why a clean email list is the foundation of healthy email delivery. 

Maintaining a Healthy Email List: Best Practices to Avoid Spam and Improve Deliverability

To keep your email list healthy, follow these tips: 

• Only add opted-in subscribers to your list: Adding recipients to your mailing list who never agreed to receive emails from you is a common shortcut to grow my list, but it’s also a path that can lead straight to the spam folder. 

• Never ever purchase or borrow email lists: Inbox providers find this practice shady, and they’ll punish senders who send to purchased lists accordingly. The same is true for scraping email addresses from the web. Just don’t do it. 

• Remove recipients who unsubscribed and keep a close eye on your email bounces: If subscribers aren’t engaging with your emails, remove them from your email list. Inbox providers will notice if many of your subscribers never open your emails or click any links—and it’s not a great look. 

6. You Have Low Engagement Rates

Why is this a problem? We already discussed the importance of getting high engagement rates. Top webmail providers have stated that they look at how many emails are opened and how many are deleted as a factor in spam filtering decisions. So if you have low open or read rates, your emails are at higher risk of being flagged as spam. You need to do everything you can to increase engagement. 

Here’s the solution: In addition to targeting the right audience from the start, you can send your emails at the right time, perfect your subject lines, segment your list, and keep your list fresh by scrubbing it regularly. 

7. Your Forms Are Being Abused 

Form abuse is a surprisingly common reason for spam placements. Spambots sniff out unprotected forms and may submit invalid (or even valid!) email addresses, often causing a great influx of hard bounces and spam complaints that will quickly impact your sending reputation negatively. Don’t let that happen. 

Protect your forms with CAPTCHA or set up honeypot fields (i.e. fields that humans don’t see but spambots do) to prevent abuse. Put safeguards in place to detect spam, for example, by blocking multiple submissions from the same IP address in a short period (those could be spam!). 

8. You Don’t Have a Working Reply-To Address Set Up

When someone hits reply on your email, what address will the response go to? As a sender, you can specify a reply-to address, and you should never use a “no-reply@example.com” address. Some spam filters and firewalls find "no-reply" email address handles to be spammy and will punish senders who use them with a higher spam score. Plus, no-reply email addresses aren’t an excellent experience for your recipients. 

The Importance of a Functional Reply-To Email Address for Better Deliverability and Customer Engagement

Email is all about communication, isn’t it? But when you’re using a no-reply address, you’re denying my customers a chance to contact you, which might frustrate them. There are cases where you might not want to receive emails back. In that scenario, we still suggest setting up a mailbox that works. 

You can browse it occasionally in case someone replies and needs help. Do you have a working reply-to email set up? Be aware that the reputation of that address matters, too. We've seen messages thrown into spam because the reply-to looks suspicious or uses a freemail domain, a common phishing or spoofing tactic. 

9. Your Emails Don’t Have a Plain-Text Version 

Spammers often don’t bother including a plain-text version of their HTML emails, so if you do not include one in your emails either, some spam filters and firewalls might find it more likely that you’re a spammer, too. So, include a plain-text version with every email you send. This doesn’t just help prove to spam filters that you’re a legitimate sender but is also valuable to recipients who don't view the HTML version within their inbox. 

Plain-text emails also make your emails more accessible because screen readers often rely on plain-text emails to read your messages. Most email service providers make it easy to add a plain-text version when you create your email. If you’re using Postmark, you can easily toggle between the HTML and text view in the email editor, making it easy to add and edit the text version of your email. 

10. You’re Using Link Shorteners

It’s not uncommon for senders to use URL shorteners like bit.ly, as they easily track clicks on links. But guess who also loves free URL shorteners? Spammers! That’s because link shorteners make hiding malicious websites and hosted files from their victims easy. 

If you’re using link shorteners in your emails, spam filters might flag your email as spam (or block your mail altogether, as we’ve seen in Gmail.) Don’t take that risk. If tracking links is essential, see if your email provider offers link and engagement tracking. 

11. You Use Open URLs

Let’s say you’re a donut shop and sending a newsletter to encourage folks to check out your yummy treats. To add a website link to your HTML email, you have two options:  

• To check out this week's special treats, visit our website.  

• To check out this week's special treats, visit donutheaven-example.com. 

Why Using Raw Links Instead of Hyperlinked Text Can Harm Your Email Deliverability

Did you spot the difference? Both emails send the reader to the donut shop's website, but the first one puts the hyperlink on the word "website," while the second one uses an open URL (also called a raw link)—that's a typed-out and hyperlinked URL. 

Don't use that second option. In our years of troubleshooting deliverability issues, we found that the latter can cause your emails to be marked as spam. Why? We can only assume that some spam filters found a pattern of spammers using open URLs, so you better be safe and don’t use them in your emails.

12. You’re Sending Suspicious Attachments 

Spammers love attachments. They might hide malware in ZIP files, sneak malicious macros into office files, or even use PDFs to get malicious code or phishing links in front of unsuspecting victims. So, it’s no surprise that spam filters are taking an extra close look at emails that contain attachments. 

If you can avoid it, don’t use attachments in your emails. If you’d like your recipients to download a file, you can make it available on your website and simply send my email readers there. That’s a few extra clicks, but it will make your email more likely to reach the inbox. 

13. Your Content-Triggered Spam Filters 

For a long time, spam filters heavily relied on content filters. Suppose you were using words or phrases commonly used by spammers that made it more likely that your emails were also placed in the spam folder. As spam filters have become more innovative and sophisticated, they rely more and more on factors like your overall sender reputation. 

How Content Filters and Spammy Phrases Can Affect Email Deliverability

But that doesn’t mean that your words don’t matter anymore. We continue to see many content filtering rules, especially when dealing with smaller receivers, including corporate mailboxes or university inboxes. For example, we've even seen mail that includes 'curse words' get rejected by university filters for being inappropriate. If you’re landing in spam and can’t find the cause in your sender reputation, authentication, or other factors listed above, look at your content. 

Remove any spammy words or phrases in your email copy, subject line, or preview text. Keep your copy concise and meaningful. If you don’t, content filters might mistakenly classify it as “spoetry”, that’s randomly generated copy that spammers use to trick receivers into thinking there’s actual content in their emails. Spam filters have become better at spotting this gibberish—but they sometimes generate false positives. 

14. You’re Using Sloppy HTML 

Sloppy HTML tends to be characteristic of spammers—spammers are busy spamming, so they don’t have the time and resources to test their email code to ensure the content renders well. While issues with your email rendering and broken HTML might not cause your emails to end up in spam right away, they can annoy your subscribers, or they might find my message suspicious and hit the dreaded “mark as spam” button as a result. 

To avoid spam caused by broken HTML:

• Use pre-built and tested email templates to ensure your code is clean, especially if you’re not an expert in email HTML. 

• Use email testing tools like Litmus to check the rendering of your emails across inboxes so I can catch errors in your HTML before you send them. 

15. Link and Image Domain Reputation and Domain Alignment 

Many senders will focus on their own sending domain reputation, which is excellent. But remember the reputation of the domains you use in your links and images! If those domains have their reputation issues, that reputation will also carry over into your message, making it harder for the message to land in the inbox. 

How Image and Link Domains Impact Email Deliverability and Spam Filters

For example, say you host your email's images on an image-sharing site. Those image-hosting sites aren’t necessarily built to host images for emails, so their domain’s reputation could be better (many spammers and phishers will host their images using these free image-hosting sites). 

Then, when you send your email that includes pictures hosted on that free image-hosting domain, receiving mail servers and spam filters will notice the domain and likely be more wary of the message. The same goes for the domains used for your email links. 

Ensuring Domain Consistency for Links and Images to Improve Email Deliverability

This is why using your domain for links and hosted images is essential. You have control over your domain's reputation and, in turn, can better control how receiving mail servers and firewalls treat your messages. Another thing that can cause issues is the need to align your FROM domain with other domains in the body of your message (e.g., for any link and image). 

For example, logos and other images are not hosted on your domain (you send them from donut@donutdonut.com, but in the body of your message, you link to donut@donut.com). You may wish to put social media icons in my email’s footers, so it’s important to note that if one of those social media domains has its own sending reputation issues (which is very common), it can carry over into your message as well—direct download links. 

Troubleshooting Spam Issues: How Aligning Domains for Links and Images Can Improve Deliverability

To summarise, exercise caution when including links and images: do not use your domain hosted on domains other than your sending domain. If you're seeing messages go to spam and you can't pinpoint the issue, try removing links and images from the message or aligning the domains and try again. If that message reaches the inbox, you'll have found the culprit! 

16. You Don't Provide an Unsubscribe Link

Imagine sending an email to a recipient uninterested in your product. Naturally, they’d want to unsubscribe from receiving further emails. But if you don’t have an unsubscribe button in the email, there is a chance that the recipient will report your email as spam, which we already know is a negative trend. So, giving users a clear way out or managing their preferences is crucial. 

17. You Have Low Mailbox Usage 

Why is this a problem? In their spam filtering algorithms, email service providers look at the ratio of active to inactive email accounts on your list. An inactive email account is an account that hasn’t been used for a long time or is rarely used. If you’re mailing a campaign to many email addresses that appear inactive, that’s a red flag to spam filters. 

To prevent this, periodically clean up your email list of subscribers who haven’t engaged with your campaigns in a while by sending a win-back email to increase engagement. This is a way of giving my audience one last chance to start engaging with their company before you remove them from your email list.

Related Reading

• DMARC vs DKIM
• Importance Of DMARC
• What Is a Soft Bounce Email
• Email Deliverability Checklist
• What Affects Email Deliverability
• Why Is Email Deliverability Important
• Email Bounce Rate
• Fix Email Reputation
• Improve Sender Reputation
• Email Hard Bounce
• Email Deliverability Tools
• Email Deliverability Best Practices
• Best Email Domains

5 Ways to Avoid Landing in the Spam Box

1. Build Your Email List Responsibly

Focus on targeted audiences to keep your IP address off the spam list. Sending the wrong messages to the wrong recipients or using the right messages to unengaged audiences can get your emails marked as spam. 

Avoid the following practices: 

• Using shared lists

• Co-registering

• Purchasing

• Renting email lists from third parties

This practice often leads to emails being sent to spam traps. Build your email list organically. Sure, developing a trustworthy plan takes time, but once you have it sketched out, you can worry less about longevity.

2. Authenticate Your Emails

Setting up proper email authentication can be tricky, but doing so dramatically increases the chances of an email landing in the inbox instead of the spam folder. Yahoo, Google, and other inbox providers focus on authenticated emails to ensure they are legitimate and safe. 

DMARC (Domain-Based Message Authentication Reporting and Conformance) influences the power of SPF (Sender Policy Framework) and DKIM (Domain Keys Identified Mail). Meeting this standard helps ensure no one can tamper with your emails during transmission. SPF checks who you are by comparing the sender’s IP with a list of IPs authorized by the domain administrators.

3. Monitor Your Email Reputation

Reputation matters when it comes to email deliverability. You can quickly land on an email deny list (blacklist) if your email domain reputation slips. This can happen if you send any spam trap emails. So, the well-intentioned and cautious senders may fall into the email deny list. 

Below are a few best practices to reduce this risk: 

• First, use real-time email address validation. 

• Remove unengaged subscribers by implementing a sunset policy. 

• Sunset policy is getting inactive users out of your email list.

4. Track Email Engagement Metrics

Tracking your emails’ engagement metrics lets you know if any changes are needed or if your email program is improving. You can also build a few baseline metrics to understand the email performance clearly. Click-through rates, open rates, and spam complaints are some metrics you can follow.

5. Improve Your Email Design, Content & Structure

There are many practices to follow while you design an email. 

A few examples are: 

• It’s easy for people to recognize you when your email aligns with the brand. It includes: 

• Logo

• Tone

• Images

• Fonts

• Colors, etc.

• Do not use spam trigger words like: 

  • "special offer" 

  • "risk-free" 

  • "dear friend" 

  • "toll-free," and more

  • Ensure your email copies are to the point, simple, and easily readable for your targeted customers. 

Optimizing Email Design: Balancing Text, Images, and Personalization for Better Engagement

Your email must be responsive for all devices, like desktop and mobile. Don’t just include images. Your text and image ratio should be balanced for a perfect email template. Make your email personalized wherever and whenever possible to enhance the user experience. If you are sending a marketing email, your email should contain a physical address. Avoid using a no-reply email address. End your email with the right salutation.

Start Buying Domains Now and Setup Your Email Infrastructure Today

At Inframail, we are revolutionizing cold email infrastructure with unlimited inboxes at a flat rate. 

We provide: 

• Microsoft-backed deliverability

• Dedicated IP addresses

• Automated technical setup 

It scales its cold email outreach efforts efficiently:

• Agencies

• Recruiters

• SDRs  

Main benefits of using our service: 

• Automated SPF, DKIM, and DMARC setup

• Dedicated email servers for each user

• 16-hour priority support daily

Unlike traditional providers that charge per inbox and leave you wrestling with technical configurations, Inframail streamlines the entire process. We handle the complex infrastructure setup while you focus on reaching more prospects. 

InfraMail provides the robust email infrastructure you need without the usual technical headaches and per-inbox costs, whether: 

• You're an agency looking to scale outreach

• A recruiter connecting with candidates

• An SDR driving sales

Start buying domains now and set up your email infrastructure today with our email infrastructure tool.

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• Soft Bounce Reasons
• Check Email Deliverability Score
• Soft Bounce vs Hard Bounce Email
• SalesHandy Alternatives
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