7 ways to Improve Email Sender Reputation in 2025

Understanding Email Sender Reputation

What is email sender reputation?

Email sender reputation plays a huge role in your ability to land in the inbox or in the spam folder of your recipients.

It is one of the 3 most important factors to determine your deliverability. The two other main factors are your email content and your sending setup.

In very simple terms, email sender reputation is 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.

If you're a good sender who sends interesting emails, follows the right sending practices, you'll get a positive email sender reputation.

If you don't follow the good practices, send irrelevant emails, 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 reputation is on two levels, the IP reputation and the domain reputation.

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

In this article, we will have email sender reputation explained in detail. If you need to know why are your emails going to spam you can check out our full guide about it.

IP 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 emails are primarily interacted with by recipients. A domain reputation score is assigned to reflect the trustworthiness of your domain.

The domain reputation is closely associated with the IP reputation.

If you send emails from an IP address with a positive email sender reputation but from a domain with a bad reputation, you may end up in spam.

You have to maintain both a positive domain reputation and IP reputation for a good email deliverability.

Depending your mailbox or email service provider, you may or may not have control on 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 particular case it's totally fine since these two major mailbox providers have highly reputable IP addresses to send your emails.

The 5 factors affecting your email sender reputation

1. Your user engagement

Positive engagement metrics, such as open rates, click-through rates, reply rates, and the rate at which emails are starred and removed from spam play an essential role in assessing email sender reputation.

High user engagement means that recipients are interested in your emails and find them relevant.

On the other hand, low user engagement can damage your email sender reputation, making it more likely for your emails to land in the spam folder.

User engagement is the best way for the major inbox provider to score if you are an interesting sender or a spammer.

Here are quotes of leading companies in the email field about that:

ReturnPath: "Gmail uses engagement as a factor for filtering your email."

SendGrid: “The higher your email engagement, the more likely you are to avoid spam filters and land in the inbox.”

CampaignMonitor: “Now, whenever you send a new campaign, inbox providers like Gmail and Outlook actually look at their user engagement and previous interactions with your past campaigns. They then use this information to determine whether your latest campaign makes it to the inbox or not.”

In 2025, using email warm up is currently the most efficient way to maximize your user engagement and improve your reputation.

Moreover, that's crucial to limit the the volume of emails sent, building a proper mailing list, and writing good emails will help increase your email sender reputation.

2. Your email service or mailbox provider

The email service provider you choose has a huge effect on your email sender’s reputation.

Selecting a reputable email service provider that is reliable, has a positive history of delivering emails, and is trusted by mailbox providers and spam filters is a game-changer to land in inbox in 2025.

In the following sections, we will discuss some of the most reputable email service providers for different types of emails, such as cold outreach, marketing or newsletter emails, and transactional emails.

3. Spam complaints

High spam complaint rates destroy your email sender reputation.

When recipients mark your emails as spam, it sends a big signal to mailbox providers that your emails are not relevant.

Minimizing the number of spam complaints you receive is very important to protect your sender reputation and maintain it over time.

4. Your sending volume

The more emails are sent daily from your domain and IP, the higher the risk to land in the spam folder.

Sending tons of emails is a spammy behavior, the fewer emails you send, the more human you behave, the more likely to land in inbox you are.

5. Bounce rate and list management

Bounce rates are a metric that reflects the number of emails that were not delivered due to various reasons, such as invalid addresses. Hard bounces, which indicate that emails are being sent to invalid addresses, can have a significant impact on deliverability and sender score.

Why? Because it says to mailbox providers that you don't really know your recipients.

Improving your email sender reputation: the 7 most efficient actions

1. Maximize your engagement rate with email warm up [GAMECHANGER]

Email warm up (or email warming) is the process of generating 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 sent while also maintaining a high engagement rate. This means sending emails that are opened, replied to, marked as important, and removed from spam.

By doing so, you demonstrate to inbox providers that you are a legitimate and interesting sender who deserves to land in the inbox.

MailReach, an email warm up tool, automates this process by gradually increasing the volume of emails and generating meaningful conversations with high reputation inboxes. The positive interactions generated during the warm up process raise your sender reputation and improve your deliverability.

2. Make sure to choose a highly reputable email service provider

For cold outreach: use Google Workspace, Office 365 or Zoho inboxes

Google Workspace (Professional Gmail), Office 365 (Exchange) and Zoho are the top 3 mailbox providers to land in your recipients' inbox according to our data.

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, Zoho address to land in the inbox of a Zoho, Gmail or Outlook account?

Choose one of these 3.

Once it's done, you can use an outreach solution that will automatically send your email sequences from your inboxes.

We recommend 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 on MailReach.

3. Authenticate your domain (SPF, DKIM, DMARC)

Authenticating your domain involves verifying that the emails you send 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.

You can check all of the above using our free SPF checker and DKIM checker tools.

4. Limit your volume of emails sent (for cold outreach)

If you're doing cold outreach, never send more than 150 cold emails per day per email address and ideally per domain.

You need to have a human behavior.

From all the tests we've done, the fewer cold emails you send daily, the better for your email sender reputation and deliverability.

So if you can send max 100 cold emails per day per email address / domain, do it.

If you need to send a higher volume per day, you have to follow the Multi Sender Strategy. We have a dedicated article on it: the best cold email deliverability sending strategy.

5. Work on your emails to minimize spam complaints (for cold outreach)

These are our guidelines :

• Use at least basic personalization like "Hi [First Name]". Use the company name as well if you can.

• Make your recipient feel selected and considered. Give him the impression you emailed him manually. At least make the person doubt.
• Focus on the value you bring or the problem you solve, not the features. At the end of the day, how do you help your 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 you follow up, the more spam complaints you get. We don't recommend more than 2 follow-ups. 3 emails in total.
• Put more space between follow-ups. Never less than 3 days between emails, we recommend a minimum of 6. Less people breathe.

A nice hack can be to ask yourself “How I'd like to be contacted, if someone wanted to email me to sell me the same thing I'm offering?”

6. Make it easy to unsubscribe (usual link and list-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 your message, they just mark your email as spam and ciao.

No clear unsubscribe link = more spam complaints = damaged reputation = you miss customers, revenue and growth.

There's no scenario in which 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.

It is the unsubscribe link or button 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.
• It's on the path between your email and the "Mark as spam" button

And that results in diminishing your spam complaint rate.

7. Take care of your email list

For cold outreach

• Always verify your emails before sending any campaign

For marketing, newsletters, transactional emails

• Use double opt-in. That helps ensure that email lists remain accurate and up-to-date.
• Remove inactive people from your list. Having too many inactive recipients lower your engagement rate, which decreases your sender reputation.

Top Tools for Checking Sender Reputation

MailReach

MailReach is a solution 100% focused on improving your deliverability, including your email sender reputation. It's composed of two email deliverability tools: a powerful email warm up service and a reliable email spam test.

MailReach’s email warm up service is designed to maximize your email sender reputation and in turn, your deliverability.

MailReach's email spam test is designed to help you test the deliverability and inbox placement of your own emails and give you helpful insights on the improvements you can make to land more often in the inbox of your recipients.

How it works

First, you have to connect your email account to MailReach.

Once it’s connected, MailReach automatically starts email conversations with real high reputation inboxes of our engagement network.

The warming emails are meaningful to build trust with the major providers Google and Microsoft.

Most of your warming emails get opened, replied positively (interested replies, understood by Google and Microsoft), marked as important and removed from spam and categories.

All this positive engagement increases your email sender reputation and deliverability. It teaches the inbox providers to send your emails to the main inbox and not in spam.

You can monitor how your email reputation is doing by checking your “Where your warming emails land” graph and you get an Email Sender Reputation Score out of 100.

Google Postmaster tools

Google Postmaster tools is an interesting solution to understand how Google treat your sending domain when your email tries to reach out to the mailboxes of their users.

To use Postmaster Tools, you’ll need to have a high sending volume. You’ll also need to add custom records to your DNS to get started. Once that’s done, you’ll be able to see how your IP and domain reputation fluctuate on a 4-level scale (bad, low, medium/fair, high).

Google will also tell you how you’re doing in terms of authentication, spam complaints, delivery errors, and encryption. 

Final word

Maintaining a good email sender reputation is a game-changer for the success of your email campaigns.

By following the strategies and recommendations provided in this blog post, you can improve your email reputation and deliverability, ensuring that your emails reach their intended recipients and contribute to the growth of your business.

Remember, a positive email sender reputation is an ongoing process that requires constant attention and, most importantly, a dedication to providing value to your recipients.

It is essential to monitor your email sender’s reputation regularly and make improvements as needed, using tools like MailReach and opting for reputable email service providers for different types of emails.

Frequently Asked Questions

How can I check my sender reputation?

By using MailReach's warmer and email spam test, Google Postmaster Tools.

How do I fix my email sender reputation?

To fix your email sender reputation:

• Minimize your sending volume or totally stop sending emails
• Maximize your user engagement with email warming
• Follow our dedicated guide : How to restore a bad sender reputation with MailReach

What affects sender reputation?

Here are the main factors that affect email sender reputation :

1. Your user engagement: how your recipient react to your emails. The more positive interactions you receive, the better for your email sender reputation. That's why email warm up is a gamechanger.
2. Your email service or mailbox provider: that's crucial. Choose your provider wisely. It makes a huge difference.
3. Your spam complaint rate: having too many spam complaints decreases your email sender reputation.
4. Your sending volume: the more you send, the lower your email sender reputation.
5. Your bounce rate and list management: the more you bounces you get, the lower your email sender reputation.