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How Email Sender Reputation Affects Email Deliverability

Find out why email sender reputation is crucial for successful email deliverability. Learn how to improve your sender score and avoid the spam folder.

Your email sender reputation can affect your email marketing metrics for better or worse. All companies communicating with their customers via email should learn what email sender reputation is and how it impacts deliverability.

Just because your business sends an email doesn't mean all your customers will get them. Email service providers (ESPs) determine a sender reputation score for everyone and every business that sends emails to determine whether or not to actually send your emails to the desired recipients.

If you have a low email sender reputation, ESPs are less likely to deliver your email to someone's inbox.

Instead, you could end up in the spam folder, or worse, your emails might not reach your customers. You should learn as much as possible about your email sender reputation to ensure your emails reach the right palace at the right time. This article will discuss everything you need to know about the relationship between email sender reputation and deliverability.

What is email sender reputation?

ESPs, also known as mailbox providers, give senders a reputation score that determines whether or not your emails will end up in someone's spam folder.

The higher your reputation score, the more ESPs trust you, and the more likely your emails will make it to your customers' inboxes. Different providers can choose how they determine your sender reputation, so having a good email sender reputation is crucial for ensuring high email deliverability rates.

Your email sender reputation is a combined score between your IP and domain reputation. Your IP reputation is the IP used to send emails, which are usually shared IP addresses. However, companies can also get dedicated IP addresses if they have a high sending volume. Each IP address has a reputation that tells ESPs if they should trust your emails and deliver them to their customers' inboxes.

Your domain reputation is similar to your sender reputation but instead measures how trustworthy your domain is, so it's more specific to your business rather than the platform you use to send your marketing emails.

Both domain reputation and IP reputation can influence your sender reputation, which impacts deliverability rates. Email deliverability is exactly what it sounds like — delivering your emails to the appropriate inboxes. You can use email deliverability rates to determine whether your campaigns are actually reaching your subscribers' inboxes.

So how does sender reputation affect deliverability? Having a poor reputation means your emails are less likely to be delivered; they won't end up in your subscribers' inboxes.

Email sender reputation is a score determined by mailbox providers that want to ensure their customers are happy with their services. Their customers don't want spam, so ESPs try to automatically filter spam by reviewing a sender's reputation.

Sender reputation is typically determined using various factors and metrics, such as:

Bounce rates

Email bounce rates tell ESPs that your emails are failing to get delivered for various reasons. There are two types of bounces: soft and hard. Hard bounces, on the other hand, indicate that you're sending messages to invalid email addresses. Hard bounces are more detrimental to your email deliverability rates and sender score because they indicate that you're either purchasing lists or not managing your email lists correctly.

Sender history

Sender history refers to the emails you've sent in the past, including the volume and frequency of your emails. If you have a history of sending lots of emails throughout the day, it's a red flag for ESPs, and they may prevent your emails from being delivered. Remember, ESPs don't want their customers getting spammed, so you're more likely to end up in the spam folder if you have a bad history.


Engagement refers to the actual performance of your email marketing campaigns, considering metrics like click and open rates. Low open rates mean your customers are not engaged and less likely to want to see your communications, so ESPs may begin sending your emails directly to spam.

Unsubscribe rates

If you have a high unsubscribe rate, ESPs assume it's because you're emailing individuals who didn't actually subscribe in the first place, which implies you've purchased your email list or are sending spam emails.

Spam complaints

Email users can report any email as spam, which can help mailbox providers automatically filter different types of spam for them. Any time someone moves one of your emails from their inbox to their spam folder, it could hurt your sender score.

Spam traps

Internet service providers (ISPs) and ESPs often set spam traps to identify spammy senders by using legitimate email addresses. Spam traps are typically found in purchased email lists to catch senders and add them to blocklists which prevent emails from that sender from being delivered at all.

As long as you have an organic (not purchased) email list and are using email best practices, you shouldn't have to worry about your sender reputation. However, if you frequently receive complaints or land in the spam folder, you should find ways to improve your sender score.

The impact of email sender reputation on email deliverability

Mailbox providers want to ensure their customers aren't receiving massive amounts of spam, so they determine a sender's reputation to decide whether or not to deliver an email. ISPs and ESPs run reputation checks before sending an email to ensure you're credible. The higher your sender reputation score, the more likely your emails are to reach the desired inbox.

How does email sender reputation affect email deliverability?

A good sender reputation makes it more likely for your emails to reach your subscribers. However, a poor sender score means it's unlikely your emails will reach your subscribers, even though it's still possible. Being labeled as a spammy sender can hurt your business, and it can even lead to your domain being blacklisted, which means your emails won't be delivered.

Additionally, email marketing platforms can suspend your account if you receive too many spam complaints, which means you won't be able to send marketing emails at all. When your email marketing account is suspended due to spam complaints, your provider will investigate if you're engaging in spammy practices.

How does email sender reputation affect email filters?

Email sender reputation can trigger email filters. Once your email is sent from your email marketing platform, it goes through a spam filter before it's delivered. If the filter determines your email is spam based on your sender reputation and various other factors, your email will end up in the spam folder.

Inboxes these days are smarter than ever, so if a customer puts your email in the spam folder, it's highly likely the rest of your emails will end up there since mailboxes learn how email users categorize certain types of emails.

However, your campaigns' past engagement is a significant factor that determines whether your emails will make it past the spam filter. If you have high open rates and click-through rates (CTRs) with minimum bounces, your sender reputation is strong, and your emails are less likely to end up in the spam folder.

Unfortunately, the opposite is also true. If your subscribers aren't opening your emails and you've received spam complaints, your emails are less likely to make it to your subscribers.

Maintaining a positive email sender score is crucial if you rely on email marketing to attract and retain loyal customers. Here are a few tips to help you improve and maintain your sender reputation for the best results:

Keep your email list clean and up-to-date

You should never purchase email lists because it will result in bounce rates, spam complaints, unsubscribes, and other red flags for ESPs and ISPs. Yet, even if you're using a purely organic email list, you should review and update it regularly.

People delete their personal or corporate email addresses all the time, whether because they've left the company or because they've simply changed their email. Unfortunately, not having up-to-date contact information can result in hard bounces that affect your reputation.

One of the best ways to ensure you have accurate and up-to-date email addresses from your subscribers is to set up double opt-in, which sends an email that asks subscribers if they agree to opt into your email communications. You can also include the double-opt-in method in your welcome email to help subscribers understand what they've signed up for.

If you don't receive a reply, then you can assume you either have the wrong email address or the subscriber doesn't actually want to receive your communications.

Focus on engagement

One of the biggest email marketing mistakes you can make is not developing campaigns that attract customers. Anyone can send an email, but are your email marketing campaigns performing?

Since engagement metrics can play a role in your sender reputation, creating email marketing campaigns that perform well is crucial. Consider different design concepts, copy, and offers that can make subscribers want to open and click through the email.

Avoid using spam trigger words

Customers don't want to open or read clickbaity emails, and email service providers have a running list of words that trigger spam filters. Spam trigger words make your email content look fraudulent, and mailbox providers can either send them straight to spam or refuse to deliver them at all. Of course, not all spam trigger words indicate that you're sending spam. For instance, the word "free" is often considered a spam trigger word because companies use it to overpromise and underdeliver.

However, if you use free in the right context, your email won't get flagged as spam. For instance, if your email really does include an offer for a free product or service, there's nothing wrong with using that word.

Monitor your email deliverability and take action if you notice issues

Every time you send an email campaign, you should monitor your deliverability to ensure your emails are making it to your subscribers' inboxes. If your email deliverability rates are low, it indicates that you've done something ESPs and ISPs consider spammy, such as purchasing an email list or getting caught in a spam trap.

Luckily, as long as you use email marketing best practices, you can maintain a good sender reputation and ensure the success of your marketing campaigns.

Avoid spam complaints and improve your sender reputation and deliverability

A strong sender reputation increases your email deliverability to attract more customers and bring them back to your website. You can use our email reports and data to ensure your emails are delivered to the right people at the right email addresses and increase engagement rates to improve your reputation.

Start sending marketing emails with Mailchimp today. Our suite of tools gives you access to everything you need to create campaigns that increase engagement and maintain a good sender reputation.

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