October 18, 2019

Email Blacklists: How to Check, Get Removed, and Avoid

Reading time about 9 min

Some emails never make it to the recipient’s inbox.  Sometimes it’s due to a hard bounce generated by an invalid email address. Other times it’s because the sender’s IP address and/or domain has been blacklisted.

Are blacklists as bleak as they sound? How easy is it to get removed from one? This article will cover all you need to know about email blacklists.

My IP/domain has been blacklisted, how did this happen?

Surprised-looking bearded man wearing blue shirt against pink background

ISPs (Internet Service Providers) like Yahoo, Gmail, and Outlook use spam filters to decide whether an email is delivered, flagged as suspicious, or rejected entirely.

Getting your emails past spam filters is crucial in email marketing to prevent your work ending up in the junk folder or worse – on an email blacklist!

If you wind up on an email blacklist, this means your IP or domain has shown characteristics of engaging in spam-related activity.

The definition of spam varies according to different ISPs and blacklist vendors. While each blacklist has its own set of rules and policies to determine spam, here are some of the typical reasons for getting blacklisted:

  • Recipient complaints
  • Emails or IPs being used for fraudulent activities (malware, phishing, hacking, ransomware, etc.)
  • IP supporting spam services like scrapers or bulletproof hosting
  • Buying email lists 
  • Getting caught in spam traps
  • Using ISPs like Gmail or Outlook to send mass emails   
  • Any other behavior considered suspicious (a high volume of hardbounces, too many emails sent within a certain period of time, technical standards not being met)

How does being on an email blacklist affect my business?

It’s likely that your email deliverability will take a hit. Deliverability here refers to the ability to land emails in a recipient’s inbox.

The impact to your email deliverability depends largely on the size and notoriety of the blacklist.

Let’s say your domain ends up on a small and relatively unknown blacklist. There’s a good chance the impact will be so minimal you won’t even notice it. This is the best case scenario.

On the other hand, if you’re on a blacklist used by a major email provider then you’re in trouble. In this case your emails are likely to be rejected before ever reaching the recipients. Naturally, this will be detrimental to your email marketing efforts. 

How to carry out an email blacklist check

You’ll know you’ve been blacklisted when your undelivered email generates an error message to inform you of the blacklisting.

If, however, you don’t receive any such message but notice a sudden drop in your delivery rates, it’s a good idea to do an email blacklist check.

One of the easiest ways to do this is to go to the websites of the most common blacklist vendors and check the blacklists directly. These sites usually have lookup tools with which you can enter the IP address or domain name and run a search. It’s that simple.

Here are some of the most common email blacklist providers:

Another option is to use one of the many email blacklist checkers available online.

If you’re looking for a free email blacklist checker you can try out tools like MXToolbox or Ultratools.

What to do if your IP or domain name is on an email blacklist

There are three things you need to do when you find out you’re on an email blacklist:

  1. Understand why this happened: Did you make changes to the email content? Were you emailing a new set of contacts? Was this part of a new email strategy?
  2. Request blacklist removal
  3. Take actions to prevent this from happening again

It’s essential that you review your email practices and make changes where necessary.

Remember, you’re on the blacklist because you were doing something wrong – it’s up to you to find it and fix it.

How to remove an IP address/domain from an email blacklist

Most of the blacklist vendors have information available on their websites about blacklist removal.

Delisting can be requested via a link or form. You just need to follow the necessary steps and put in place the recommended actions to improve your email marketing practices.

Ideally you want to establish new rules and practices for yourself so that you don’t appear on any more blacklists. Ever. ?

How to avoid ending up on a blacklist in the first place

Prevention is certainly better than cure when it comes to email blacklists.

It’s going to be much better for your email marketing performance and brand reputation if you abide by email deliverability best practices. This way you can minimize the blacklist risk entirely – while maximizing the impact of your email campaigns.

Here are some email marketing best practices to prevent you from being blacklisted:

Always obtain consent 

Only email contacts who have given their express permission for you to do so. For signups we strongly recommend implementing a double opt-in process to confirm the subscriber’s intent and ensure the address provided is valid.

Double opt-in is one sure way to protect yourself from spam traps (more on those below).

Keep your contact list up to date

Keep in mind that engagement has an impact on deliverability. If a contact hasn’t opened an email from you in six months, then it’s time to delete. Unengaged contacts are more likely to mark you as spam if you keep hounding them with emails (not cool).

Remove them along with any unsubscribes and inactive addresses as part of regular list cleaning.

Don’t send mass email from an ISP

Webmail providers (e.g. Gmail, Yahoo, Outlook) are designed for personal use so when a mass email is sent from one of them, it looks suspicious.

The best way to send and manage mass email campaigns is by using a dedicated email marketing service like Sendinblue.

Keep a close eye on campaign analytics

If you notice a sudden drop in your email open rates you can be sure that something’s up. Tracking campaign analytics closely will allow you to react quickly in the event of a deliverability issue or blacklisting.

To get real-time campaign updates outside of your ESP’s application you may want to consider setting up a webhook.

Check your sender reputation

Your sender reputation is one of the criteria used by ISPs to determine if you’re a bad sender. Your sender reputation depends on how your emails have performed in the past and whether your domain has been flagged for suspicious activity.

You should check up on it regularly using tools like Senderscore.

Avoid spam words in subject lines and email copy

Did you know that spam filters are triggered by certain words and phrases? Check out this list from Elegant Themes to know which ones to avoid.

And finally…never buy email lists!

Just think about it: Buying a list of dubiously sourced random email addresses of people who’ve probably never heard of you and definitely didn’t opt-in to receive your emails. When would that ever be a good idea?! We’ll shout it from the rooftops if we have to – don’t buy email lists! 

Not only is this more important than ever in light of the GDPR, you should also be aware that purchased contact lists are full of spam traps (also known as ‘spam honey-pots’).

A spam trap is an inactive email address that has been purposely left out in the open by ISPs and blacklist vendors. Because the address is inactive, the ISP or blacklist vendor knows that any email received is unsolicited – and this identifies the sender as spammer.


By now you should know a lot more about email blacklists and how they work.

Only send your marketing emails to contacts who actually want to hear from you and be sure the content is providing value in some way.

Signing up to a reputable email service provider is one of the best ways to manage emails and optimize your deliverability.

Why not take Sendinblue for a test-drive and see how it goes? Signup is quick and our free version lets you send 9,000 emails per month (or 300 per day).

Open my free Sendinblue account >>

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