You've crafted the perfect email. The design is on brand, the copy is engaging, and you've even personalized it for your target recipient. But when you hit send, your email gets stuck in purgatory — never reaching your contact's inbox delivery. Instead, it’s bounced back or sent straight to the spam folder. Email deliverability can be frustrating, turning your email marketing efforts into a game of chance. The good news is you can improve your odds of success by understanding why emails get stuck or lost and how to improve the sender’s reputation.  Improving sender reputation can help your emails reach the correct destination rather than getting lost in the email abyss or stuck with the wrong crowd.

Table of Content

• What is Email Sender Reputation?

• 15 Strategies to Improve Sender Reputation

• Start Buying Domains Now and Setup Your Email Infrastructure Today

What is Email Sender Reputation?

Email sender reputation reflects how mailbox providers (like Gmail or Outlook) and Internet service providers (ISP) perceive you as a sender. It’s a score assigned by a mailbox provider (like Gmail or Outlook) or an Internet Service Provider to evaluate an email sender's adherence to guidelines and sending habits. 

Email Sender Reputation for Better Deliverability

If you're a good sender who sends interesting emails and follows the right sending practices, you'll get a positive email sender reputation. If you don't follow good practices, send irrelevant emails, and receive spam complaints, you'll get a bad sender reputation and end up in spam. In most cases, you don't have access to this reputation score; it's a black box, but you can use external tools such as MailReach to evaluate it. 

The email sender’s reputation is on two levels: 

• The IP reputation

• The domain reputation

A poor sender reputation will directly impact email deliverability, resulting in emails not reaching their recipients, as mailbox providers may block or filter them.

What Are IP Reputation and Domain Reputation?

IP reputation is based on the IP addresses used for sending emails. A good IP reputation can be damaged with a single unsuccessful email campaign, leading to a lower IP reputation score and emails landing in spam. 

Domain reputation evaluates the behavior of a domain based on its past actions. It is determined by the rate at which recipients primarily interact with emails. A domain reputation score is assigned to reflect the trustworthiness of your domain. The domain reputation is closely associated with the IP reputation. 

The Importance of Balancing IP and Domain Reputation for Optimal Email Deliverability

You may be in spam if you send emails from an IP address with a positive email sender reputation but from a domain with a bad reputation. You must maintain a positive domain and IP reputation for good email deliverability. 

Depending on your mailbox or email service provider, you may or may not have control over your sending IP. Typically, if you send emails from a Google or Outlook mailbox, IP addresses are managed by Google or Outlook; you don't have control. But in that case, it’s okay since these two major mailbox providers have highly reputable IP addresses to send your emails.

What Impacts Email Sender Reputation?

Here are some components that determine your IP and domain reputation, which, in turn, determine your sender reputation: 

Email Content

Are you sending high-quality emails that your subscribers want to receive? Email content that contains spammy characteristics or wording is flagged as low-quality emails. All-image emails and messages that are too large may also look like red flags to ISPs. You don't want mailbox providers to think you're a spammer. 

Abuse Complaints

Do your subscribers mark your emails as spam? This is called an abuse complaint. A high complaint rate might trigger spam filters and negatively impact your sender’s reputation. To avoid receiving abuse complaints, make it easy for your readers to unsubscribe when they no longer want to receive your messages. 

Email List Quality

Your reputation goes beyond your email content itself. For example, if you don't maintain your mailing list through regular email verifications, you risk having spam traps or invalid email addresses as part of your list. This results in a high bounce rate, which sends a red flag to mailbox providers because it appears like your content isn't welcome.

Sending History

Okay, this one is a chicken-and-egg problem. If your IP address has not consistently sent mail, you’ll need to “warm up” your IP before sending email marketing campaigns at scale. Also, if you have a spotty sending history, you’ll be flagged as a potentially problematic sender, which will, in turn, cause problems with your email sending.

Related Reading

• Why Are My Emails Going To Spam
• 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
• Email Sender Reputation

15 Strategies to Improve Sender Reputation

1. Know Your Sender Reputation Score

Your sender reputation score is the first thing you must look at when you want to improve your reputation. The rule of thumb is that you want to be above 90. But if it falls between 50 and 90, you should look at what’s happening and see where you can improve your score. If you fall below 50, you need to act fast. Things are severe if you are below 50. You can check your sender reputation score in a few different ways. 

Top Tools and Metrics to Monitor and Improve Your Email Sender Reputation

Here, we’ll list a few to get you started: 

• There is SenderScore.com, which will measure your reputation from 0 to 100. 

• The higher the score, the better your reputation and deliverability rate. 

• Numbers are calculated on a rolling 30-day average, where it will rank you against other IP addresses.

• A real-time database of IP addresses, where they rank you with either a ‘poor’ or ‘good’ reputation. 

Some of the tools you can use to check the sender reputation score:

• Provided by Barracuda Networks, under their Barracuda Reputation System. 

• Another tool you can use is Google Postmaster Tools. Google offers its Postmaster Tool, which allows you to track data at a high volume and send it to Gmail. They provide IP reputation, domain reputation, Gmail delivery errors, and more. You can also measure your reputation by tracking your email marketing metrics. Look at your open, click-through, bounce, and engagement rates. These are the KPIs you need to be looking out for. 

2. Maximize Your Engagement Rate with Email Warm-Up

Email warm-up (or email warming) generates positive user engagement to an email address to build and maintain a positive email sender reputation (IP and domain reputation) with mailbox providers. 

Email warm-up involves gradually increasing the volume of emails while maintaining a high engagement rate. This means sending emails that are opened, replied to, marked as necessary, and removed from spam. Having a consistent strategy for warming up an IP address is helpful. 

Most teams use a 30-day newsletter warm-up that goes as follows: 

• Divide your monthly email volume by 30 

• Spread the desired volume over thirty days 

• Start sending out emails evenly based on the calculation 

• Start every campaign with a welcome message 

• Create a subdomain purely for email marketing 

• Have a 5:1 ratio of the newsletter and transactional emails. 

3. Choose a Highly Reputable Email Service Provider

Make sure to choose a highly reputable email service provider. 

These are the top 3 mailbox providers to land in your recipient’s inboxes according to our data: 

• Google Workplace (Professional Gmail)

• Office 365 (Exchange)

• Zoho 

All the other ones offer a much lower deliverability. And that makes total sense: Google, Microsoft, and Zoho own most of the mailbox market. Who's better than a Gmail, Outlook, or Zoho address to land in a Zoho, Gmail, or Outlook account? Choose one of these 3. 

Once done, you can use an outreach solution to send email sequences from your inboxes automatically. We recommend: 

• Inframail

• Emelia

• Reply.io

• Apollo

• Outreach

• Mixmax

For opt-in emails, use: 

• Brevo (ex Sendinblue) 

• MailChimp

• Mailerlite

• SendGrid

From our data, these are the ones who demonstrate the highest email reputation scores. 

4. Authenticate Your Domain (SPF, DKIM, DMARC)

Authenticating your domain involves verifying that your emails are from a legitimate source. This is achieved by setting up SPF, DKIM, and DMARC records. By authenticating your domain, you reduce the chances of your emails landing in spam or not being delivered at all, ultimately improving your sender’s email reputation and deliverability. 

5. Send Emails in Small Batches

Most experienced teams start with an IP warm-up before they dive into email marketing campaigns. Since the volume and frequency of emails are highly important when it comes to IP reputation, do not send too many letters at once. Instead, segment your user base and send emails in small batches, with moderate frequency (not higher than a few times a week). 

6. Adopt a Consistent Campaign Schedule

Another reason your sender score can fluctuate is a sporadic sending schedule. Your audience is unhappy with the lack of consistency, so adopt an established frequency for your email marketing campaigns. This way, you will be able to connect with readers, ensure they have a habit of reading your newsletters, and avoid sending spikes that damage the sender score. 

7. Correspond With Domain Category

Make sure the topic of your emails corresponds to the domain category. Domains are grouped by category depending on their content, type of product, or service. For instance, a dating website will be listed in the ‘Dating’ database. 

Whenever you plan an email campaign or design a content infographic, remember the domain category it belongs to. Discrepancies between the domain’s topic and the message’s content will lower your sender score. 

8. Review Your Email List

Another efficient way to improve the sender’s reputation is by reviewing the subscriber base. Sending messages to non-existent or unengaged readers will increase your campaign’s bounce score, also taking the sender score down. Make it a habit to review the email list every once in a while. Look at how every audience segment interacts with emails, who is more likely to flag your letters as spam, etc. 

Then, there’s a particular type of subscriber–contest participants. If you have run a giveaway as a part of Black Friday content marketing and still have users’ addresses, don’t mix them with engaged readers. Instead, start slowly warming these readers up by sharing tips, guides, and other valuable content before moving to promotional emails. 

9. Be Mindful of Email Frequency

The truth always lies in the middle in email marketing–this also applies to email frequency. Too many emails are easy to burden readers and gain dozens of unsubscriptions. Too few, however, will not allow you to stay in touch with the audience and connect with prospective leads. 

Jeremy Boudinet, Marketing Manager at Nextiva, believes “one email per week is a good starting point for email frequency.” As you grow a loyal user base, consider scaling the number of letters to two per week. Top email marketing teams can even deliver daily emails. This type of engagement takes years of audience warm-up. 

10. Check for Blacklists

If your emails are continuously not performing well, it could be that you have been cited on one or more blacklists. 

Here are a couple of tips to help get you off any blacklists: 

• Self-service removal. There are some blacklists out there where you can remove your IP address from the blacklist without too much hassle. You will want to ensure I have any issues resolved before doing so because if I don’t and your IP address gets listed again, it won’t be as easy to remove the next time. 

• Time-based removal. Most blacklists have a built-in and automatic process that will remove lower-level listings, but if an IP address has sent spam more than once or at a high volume, the period will be extended. You catch more flies with honey than with vinegar. When you’re trying to get off a blacklist, you’ll get farther along if you follow the rules and cooperate. The more open and direct you are with a listing database, the easier it may be to have your IP address taken off the blacklist. 

11. Keep Your Email Strategy Fresh and Engaging

Users will get tired of seeing duplicate emails or the same information repeatedly. Keep your email campaigns interesting, and always provide value with each email you send. This could be adding a case study for them to read and help further their business or promotional information that will keep my business in their minds for future searches. 

12. Minimize Spam Complaints for Cold Outreach

These are our guidelines: Use at least essential personalization like "Hi [First Name].” I can also use the company name. Make the recipient feel selected and considered. Give him the impression I emailed him manually. At least make the person doubt. Focus on the value I bring or the problem I solve, not the features. At the end of the day, how do I help my recipient? Don't be too pushy, and have a friendly, helping approach. 

Don't send too many follow-ups. Sending follow-ups works, but the more I follow up, the more spam complaints I get. We don't recommend more than two follow-ups—three emails in total. Put more space between follow-ups. Never less than three days between emails; we recommend a minimum of six. Fewer people breathe. A nice hack can be to ask myself, “How would I like to be contacted if someone wanted to email me to sell me the same thing I'm offering?” 

13. Make It Easy to Unsubscribe

Put an easy-to-spot unsubscribe link. Not including a clear unsubscribe link in your emails results in getting more spam complaints; that’s mathematical. And no, saying “to unsubscribe, reply unsubscribe to this email” does not help. Most people don't care about replying to my message; they just mark my email as spam and ciao. No clear unsubscribe link = more spam complaints = damaged reputation = you miss customers, revenue, and growth. 

Improving Email Deliverability and Sender Reputation with the List-Unsubscribe Feature

There's no scenario where not including an unsubscribe link is better for your results. If you can, add the "list-unsubscribe.” The official definition of list-unsubscribe is as follows. The list-unsubscribe field describes the command (preferably using mail) to directly unsubscribe users by removing them from the list. The unsubscribe link or button is displayed next to the email sender information. 

The list-unsubscribe is a great tip to protect your sender reputation for two reasons: It's super user-friendly for your recipients to opt out. They don't have to search through your email to find it. And it's on the path between my email and the “Mark as spam” button. And that results in diminishing my spam complaint rate. 

14. Avoid Shared IP Addresses 

As mentioned above, using a shared IP means sharing your IP reputation with other senders. Of course, this can be good if you’re a new sender and want to piggyback off an IP with an established reputation. This can backfire if the other senders on your IP have nasty email-sending habits. Use a dedicated IP address to avoid these problems.

15. Don’t Buy Email Lists 

This is a surefire way to disaster. Purchasing email lists will likely lead to higher complaint rates when recipients mark your content as spam if the emails you bought are all legitimate. 

Purchased lists are not validated, and the recipients have not opted-in to receive messages from your service. Even if you think these lists might contain some legitimate leads, the risk to your sender’s reputation is too high.

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
• Email Hard Bounce
• Email Deliverability Tools
• Email Deliverability Best Practices
• Best Email Domains

Start Buying Domains Now and Setup Your Email Infrastructure Today

Inframail is transforming cold email infrastructure with unlimited inboxes at a flat rate. The service provides: 

• Microsoft-backed deliverability

• Dedicated IP addresses

• Automated technical setup 

It scales its cold email outreach efforts efficiently:

• Agencies

• Recruiters

• SDRs    

The Benefits of Using Inframail  

The main benefits of using Inframail's cold email infrastructure include: 

• Automated SPF, DKIM, and DMARC setup

• Dedicated email servers for each user

• 16-hour priority daily support

Unlike traditional providers that charge per inbox and leave you wrestling with technical configurations, Inframail streamlines the entire process. The complex infrastructure setup can be daunting, but Inframail handles all the email tech, so you focus on reaching more prospects. 

Inframail provides the robust email infrastructure you need without the usual technical headaches, whether you're: 

• An agency looking to scale outreach

• A recruiter connecting with candidates

• An SDR driving sales

Related Reading

• Email Monitoring Software
• Soft Bounce Reasons
• Check Email Deliverability Score
• Soft Bounce vs Hard Bounce Email
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• GlockApps Alternative
• MailGenius Alternative
• MxToolbox Alternative
• Maildoso Alternatives