If you’re sending email campaigns to your email list, monitoring email deliverability is a best practice that you must internalize. It’s not some backend tech thing for your developer to worry about. It’s literally one of the top five key priorities of email marketers. You monitor it so you can maintain it. Protect it. Improve it.
And for you to be able to do that, understanding the sender reputation is essential.
In this article, we answer what sender reputation is along with the best practices to improve it and avoid problems that could harm your email deliverability.
So, in this post, we’re answering the big questions email marketers like you are asking:
- What the heck is sender reputation, anyway?
- What does it have to do with email deliverability?
- And most importantly—how do you keep it in top shape?
What Is Sender Reputation?
In their latest infographic, Email Marketing Trends 2025, Email Mavlers pulled insights from some of the biggest names in the industry. And one theme came through loud and clear: email deliverability is getting a serious make-over.
Inbox providers have been stepping up their game, rolling out smarter spam filters, stricter policies, and new inbox features. The result? Higher standards for senders and a tougher fight to stay out of the spam folder. Sender reputation is no exception.
Imagine your sender reputation as your brand’s credit score for email. Only instead of banks, it’s Gmail, Outlook, and their mailbox provider pals judging your trustworthiness as an email sender.
It’s closely intertwined with your email deliverability. Better reputation scores mean better inbox placement for your campaigns. Whereas a low sender reputation score might get your emails caught in bounces, spam traps, or blocklists.
But, yes, every mailbox provider uses different criteria. Gmail’s standards aren’t the same as Outlook’s or Yahoo’s. Each has unique algorithms evaluating your sending behavior.
Then, how to check your reputation, you ask? The process is straightforward and completely free. Tools like Google Postmaster Tools, Microsoft SNDS, and Sender Score provide a snapshot of how mailbox providers perceive you.
So, what affects your sender reputation? Let’s break it down.
Meanwhile, Andrew King, creator of EmailStack and EmailLove, shares insider deliverability tips with Mavlers in this video. Worth your time.
Key Factors That Affect Sender Reputation (And Thus, Deliverability)
1. Your Sending Behavior
If you suddenly go from sending 1000 emails to a steep rise to 10,000 emails in a short span, mailbox providers get suspicious. Because such a sending pattern has a semblance to that of spammers.
2. Subscriber Behaviour
Positive subscriber activities—opening, reading, and clicking through your emails—providers take it as a sign you’re a legit sender. But if subscribers ignore you, delete without reading, or, worst of all, slam that “mark as spam” button, your reputation tanks.
3. Email List Hygiene
A clean list = strong sender reputation. Mailing dead addresses, inactive contacts, and spam traps destroys your engagement metrics. That’s why proactive list hygiene keeps your sender health in check and helps you avoid blocklists.
4. Email Authentication
This is that boring-but-crucial technicality you don’t skip if you want to be identified as a legitimate sender by mailbox providers. Without setting up email authentication protocols—SPF, DKIM, and DMARC—your emails are more likely to get flagged or spoofed.
Mailbox providers won’t take this lightly, as they are determined to protect their end users from phishing attacks. And with Gmail and Yahoo’s stricter stance in 2024 sender requirements, proper authentication is mandatory to support good sender reputation.
5. Your IP and Domain Reputation
Your domain represents your brand’s sending track record and trustworthiness. A solid reputation tied to your domain shows that your brand has a trustworthy history.
While your IP declares your recent sending behavior. The longer and cleaner your history with a specific IP address, the more trustworthy you look. This signals to providers that you’re a legitimate sender with genuine subscribers and proper practices. And if you’re using a dedicated IP, having a long-standing, consistent sending record can work in your favor.
On the other hand, spammers tend to move around frequently. They jump from one IP to another to dodge blocklists and filters, which means they never build a reliable reputation. That inconsistency alone can send up a red flag.
Here’s a quote worth wearing on a T-shirt. Chad S. White, Head of Research at Oracle Digital Experience Agency, says:
“IP reputation remains important, but domain reputation has become the dominant factor. The change puts greater responsibility on senders to maintain clean practices. Because while you can change your IP or subdomain to shake off a bad track record, you can’t easily switch your main domain without disrupting your entire business.”
How To Protect and Improve Your Sender Reputation
While tools are great for keeping tabs on your sender reputation, they’re just part of the picture. If you really want to boost your sender reputation, you’ll need to follow these proven tips:
1. Follow the email list hygiene
If your email list is full of outdated spam traps and “@gmial.com” typo email addresses, you’re begging for sender reputation trouble.Sending to these addresses triggers bounce issues that hurt your standing. And all of that chips away at your sender reputation.
Regularly verify your list. Remove invalid addresses, inactive subscribers, and other such bad contacts. Better yet, go for a double opt-in. Yes, it adds one extra step for the subscriber, but it also makes sure you’re not sending emails to bots.
2. Watch your send frequency
Don’t be a clingy sender. Email fatigue is the fastest way to unsubscribe or spam complaints. Email overload destroys engagement and crushes your sender score. At the same time, inconsistent sending raises red flags for both subscribers and mailbox providers.
Instead, let subscribers set their own preferences. Ask what they want to hear about, how often, and in what format. So find a sending cadence that works.
3. Make it ridiculously easy to unsubscribe
Look, no one likes losing subscribers. But if they do, make it simpler. Make opt-outs obvious and painless. If they can’t find it, they’ll mark you as spam.
4. Send high-quality, relevant content
It sounds simple: send good content. But let’s be honest—what you think is great and what your audience wants might not be the same thing.
To keep people opening and engaging, your content needs to hit the right notes. That means:
- Writing for your readers, not your brand
- Personalizing based on interests and behavior
- Including content people find useful, entertaining, or actionable.
Wrapping Up
Mailbox providers want to keep inboxes safe and spam-free. Savvy brands recognize this and work with providers, not against them. When you work toward a strong sender reputation, you’re not just following the rules; you’re setting up real deliverability results.
