Help! I'm on an email blocklist, how do I fix it?

OMG. I’m on a blocklist! FML. Getting blocklisted happens to a fair number of email marketers, and while it can feel like the end of the world, it doesn’t have to be. Read on for the inside scoop on email blocklists, how to detect if you’ve been added to a blocklist, and how to get off them instead of banging your head against a wall.



If you find that either your domain name or IP address is on an email blocklist, it’s easy to freak out. You certainly wouldn’t be alone if you did.

The term "email blocklist" was originally called "email blacklist." However, the email industry has transitioned to the term "email blocklist," and we’ve updated this post to reflect the change.

Getting blocklisted could tank your email deliverability, ruin your upcoming KPI report, and lead to a super awkward conversation the next time you meet with your boss. But don’t burn down your email server just yet. Here’s the good news: Having your domain name or IP Address listed on a blocklist is not the end of the world.

What are email blocklists?

Email blocklists exist to protect subscribers from spam emails using spam filters. In the early days of email, before blocklists, any email sender could send to any recipient if they had the address.

Contrary to what many believe today, email spam has declined, as far as the percentage that reaches inboxes. Google, for instance, claims to be blocking 100 million spam messages every day. So, while there continues to be a proliferation of spam, you may be surprised to learn that most of it never shows up in your inbox or your spam folder.

Blocklists have a lot to do with this. Like you might block that ex who still drunk texts you every other Friday night. Blocklist organizations seek to identify sources of spam and cut them off from sending annoying, unwanted, or even damaging messages.

Another way mailbox providers are combatting spam is by enforcing sender requirements. Gmail and Yahoo announced enforcement of some key requirements back in October 2023. As of February 2024 we’re starting to feel the impact. Learn more and see if your email program is up to snuff in our post on the Gmail and Yahoo sender requirements.

Once an IP address or domain name gets placed on a blocklist, the mailbox service providers will use that information to block future emails coming from those sources. The goal is to reduce spam and, in particular, the costly and debilitating scams and malware that often come with it. This helps protect their users and provides a better experience. For a more complete guide to email blocklists, here’s everything else you need to know.

Landing on a blocklist doesn’t mean you should call into question your ability to manage a successful email campaign. In fact, it’s quite common for email marketers across the industry to get placed on a blocklist every now and then.

Not all email blocklists are created equal. To find out more about the blocklists that do directly impact the delivery of your email, go here.

Why are blocklists bad?

The motivation for email blocklists is good – internet service providers (ISPs) reference them as part of the filters they use to help keep scams, spam, and malware from reaching email users’ inboxes.

The problem is, sometimes legitimate email senders can end up on blocklists. If that happens to you, subscribers who want and expect to hear from you may stop receiving your emails. Your open rates can plummet. It’ll cost you time and money to fix the problem, plus the opportunity costs of being out of touch with subscribers. And it can be very frustrating when you assume people have received emails that you sent, when in fact they haven’t.

Meanwhile, they’ll wonder why you stopped sending them emails, or may just forget about you altogether.

On both sides of the email transmission, blocklists are bad for legitimate senders.

How do you end up on blocklists?

There are several ways. If too many of your recipients mark you as spam instead of opting to unsubscribe, that can get your IP address or domain blocklisted. You can also get there if your email sending habits change dramatically, such as going from sending a few per month to sending every single day, or greatly increasing the size of your email list all at once because you purchased an email list (a big no-no).

With the new sender requirement from Gmail and Yahoo, senders are required to keep their spam complaint rates below 0.3%. Learn how in our post: How to keep your spam complaint rate low.

You can also get blocklisted if too many of your emails bounce repeatedly. This is a sign you’re not managing or paying attention to your email metrics – a common trait of spammers who tend to be, like Winnie the Pooh, of ‘very little brain.’

As a professional-grade sender, you need to be proactive in this approach — it’s not the responsibility of your Email Service Provider (ESP) to keep you off of these lists.

If you haven’t already, you may also want to look into adding email authentication protocols to your DNS to protect your sender reputation.

How to find out if your email has been blocklisted

There are several blocklists that are managed by a few different companies, so it will take some digging to check them all. You can also get some help from your email service provider, such as Mailgun, if they offer a blocklist monitoring service.

As an example, here’s one blocklist manager’s page, called Spamhaus, which uses a blocklist checker that has an IP address and domain name lookup tool to see if you’re on any of their blocklists.

Other influential blocklist companies include Spamcop, Passive Spam Block List (PSBL), Invaluement, SenderScore, and Barracuda. Go to their websites and use their online tools to see if you’re on any of their email blocklists.

If you send out an email to your list and get error messages kicked back, don’t just ignore these. If you have been blocklisted, these will usually indicate as such and include a URL to begin the blocklist removal process.

It takes work to regularly check that you haven’t gotten on a blocklist again. That’s why Mailgun offers a blocklist monitoring service. You can focus on your business and get notified if your IP address or domain ever end up blocklisted.

Spam Trap and Blocklist Monitoring from Mailgun Optimize provides insight into how often you are sending to pristine, recycled, and typo spam traps, and automates triggered notifications when your IP shows up on major blocklists. Identify issues in near-real-time so you can protect your sender reputation and avoid serious disruption to your email program.

How to get removed from email blocklists

Most reputable blocklist vendors will have a clear self-service path to delisting. This will involve sending over your contact information and any comments about what you’ve done to fix the reason for the block. Others will provide a case-specific email address and subject line.

For major domain name system blocklists (DNSBLs) like Spamhaus and Spamcop, you can – and should – ask for specifics regarding the offending traffic and find out why the blocklisting occurred in the first place. Hopefully they can share some details about what caused it, which might relate to the From, Subject, or sending domain on a dedicated IP address.

This information can help you target the issue and solve it, and it’ll go a long way when communicating back to them about what you’ve done to justify being delisted. Granted, most blocklists are automated, and a delisting request is likely to be approved at first. But after a period of time they will begin analyzing your traffic again for spammy behavior.

This means that you shouldn’t try to get delisted from a blocklist until you have actually fixed whatever landed you there in the first place. Otherwise, you’ll just get put right back on it again.

In brief, that’s what you need to do if you get blocklisted. But the best way to handle blocklists is to take proactive steps that reduce your risk of ever getting on one in the first place. We’ll look at a few such steps in a moment. As we like to say at Mailgun, “best practices will produce best results.” (Yes, it’s true, and yes, we are dorks.)

As a benefit of Mailgun's managed service, our team of email experts has developed automated monitoring of all major blocklists to check them in real time, and we'll step in to deal with the blocklist providers directly. Basically, this allows you to focus on the more important aspects of your business while we help you get off blocklists.

Our top three ways to stay off email blocklists 

Blocklists use spam traps. Spam traps are email addresses that were created to catch spammers. Some spam traps are invented specifically for this purpose, meaning that anyone who emails them is a spammer. Others are reconditioned from previously valid email addresses.

There are three key aspects to keep in mind to avoid these spam traps and stay off blocklists: List acquisition source, subscriber engagement, and list management. Here’s a brief look at all three.

 1. Do not buy or rent recipient lists

Rented and purchased email lists are filled with a number of pitfalls, we’re talking invalid addresses, pristine spam traps that were scraped from a website, and old abandoned email addresses that may now be spam traps. Additionally, recipients on these lists have not completed an opt-in for your email messages, which will produce more spam complaints and kill your email delivery rate.

A number of blocklists track high complaint rates to help identify spam and abuse, so it’s best to stay clear of any purchased list.

2. Monitor recipient engagement

As spam traps are not maintained by a real user, these recipients will have zero engagement with your messages – be they an email marketing message or a business receipt. So there is no advantage at all to keeping these emails on your list.

You can eliminate the potential presence of spam traps on your email list by creating a segment of non-engaged recipients and sending them a last-chance re-engagement campaign. Then, delete all who don’t respond. Or, you can just remove them from your list without notice.

3. Clean lists with email verifications

If you’ve had your email list for a while and – after reading this article – are worried some of the emails on there might be abandoned and potential spam traps, there is a solution.

You can do what’s called email verification. This process can be done in bulk with your entire list using Mailgun Optimize email verification. This one-time step will seek to validate all the emails on your list using your own engagement history with them, as well as data known about each email address from other sources. Any invalid emails can then be deleted or set aside.

Email verification can also be used on an ongoing basis every time a new email subscriber gets added to your list. Why might you want to do this? They may give a fake email address upon signup. They may misspell their email address – we’ve all committed easy typos. These and other reasons are why top-performing organizations are turning to email verification to ensure their lists remain clean and free from questionable emails. It’s all part of good list hygiene – which helps you smell better to incoming mail servers. Good hygiene keeps your bounce rate down and your engagement metrics up.

Again, the best way to get removed from a blocklist is to never get added to one in the first place. Email verification is the single best tool to help make that happen. It checks that email addresses are valid before a subscription is confirmed, and regularly cleans your list to keep it in top shape.

See 8 more ways to stay off blocklists.

Wrapping up

Using these best practices and managing your email reputation can be difficult to keep up with over time, in addition to all the other things you have to do.

That’s why Mailgun has the experts and tools to take care of this for you. With email verification and other services we offer, you can increase your chances of staying off email blocklists, and also get help removing yourself from them if it ever happens. Talk to one of our sales droids about email verification and avoiding and getting removed from blocklists.

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