Email Blacklist: What is it and How to Avoid or Fix it

Email Blacklist: What is it and How to Avoid or Fix it

An email blacklist is a database that uses criteria to determine if an IP is sending email it considers to be spam. In simple terms , it is a database with email addresses, IP addresses, and domain names that are known to send spam. There are several blacklists with its own unique way of taking inbound emails and determining if it is considered spam or not.

Email blacklists can be used by any and everyone, from service providers like Google and Microsoft to Internet Service Providers (ISPs) and they are used to prevent spam emails from entering their servers and annoying their customers.

Email blacklist: what are they and how to avoid or fix them

Who Influences the Email Blacklist?

Irrespective of the quality of emails you send, making a tiny mistake can make your domain blacklisted. Hitting spam trap email addresses can also lead to an immediate blacklist of your sending domain and IP address on multiple DNSBL services.

Anti-Spam vendors and the normal recipient user of your email can influence the blacklisting of email sender domain or IP address. 

  1. Spam Traps or HoneyPot Email Addresses

These are email addresses that appear just like an ordinary email address. They are primarily owned by the anti-spam agencies and MSPs. Their sole aim is to distribute trap email addresses across the internet to check if someone is sending emails to non-opt-in users. Most of the harvested or third party email list contains a few spam trap email addresses. Hitting a single spam trap can influence the real-time blacklisting of your sender domain and IP address.

  1. The Email Recipient

The email recipients are passive influencers in the email blacklisting. The open SMTP protocol allows the sending of any kind of email to any of the recipients, and there are usually no restrictions or protocol-level check. Despite the numerous anti-spam software available, it’s still tough to catch and hold all sorts of spam. In order to avoid spam, most MSPs provide a button such as “Report as spam” that gives recipients the opportunity to give their feedback, and if there are enough flags raised against your email, then there is a very high chance of your domain getting added to the blacklist. Note that high complaint rates are often produced by sending emails to recipients who have not completed an opt-in, and such practice is actually illegal in many countries.

  1. A Sudden Increase In Email Volume

This is one mistake that is common for all new marketers. Shooting up email volumes suddenly signals that you might be sending emails to an email list you didn’t build on your own but acquired on an external source. It is very unlikely that you will get many subscribers in a single day. 

  1. Hacked account

This is perhaps the most common reason why legitimate email users end up blacklisted. Numerous accounts get hacked and used by spammers who use such accounts to send spam emails. The sad thing about this is that the rightful owners might not notice till the amount of available free storage space reaches zero due to the bulk emails that have been sent by the hackers. 

  1. Email spoofing

Most people tend to disbelieve this, but the truth is that it is quite easy for people to create messages with a forged sender address. Such messages will then appear to have originated from someone other than the real source and as such spammers find them useful.

  1. Dirty mail list:

For those who use email for marketing purposes, there is a possibility that they created a list of email addresses that they reach out to via emails and newsletters. If you fall under that category, then it is important that you ensure, constantly, that your email list does not contain old email addresses that would reduce your engagement rate.  

Email blacklist: what are they and how to avoid or fix them

What are Some Signs of Being Blacklisted?

If you are blacklisted, you would be unable to send emails to the recipient’s mailbox properly. Mostly, your emails can be dropped at the recipient’s MX server and as such, giving you a bounce code. But this doesn’t mean that you will entirely be blacklisted from every mail server in this world.

If you are blacklisted on a particular DNSBL service, there are other email blacklists on the internet you can use. You have to understand that MSPs can have other email filtering mechanisms to filter out spam emails other than blacklists.

Some instances that show you might have a problem with your domain or IP being added to an email blacklist includes an increasing number of dropped Emails, deteriorating delivery rates or a high number of Email bounce rates.

Email blacklist: what are they and how to avoid or fix them

What to do If Email Was Blacklisted?

If you suspect at any time that your email got blacklisted, you should do a quick email blacklist check using one of the numerous email blacklist checkers available on the internet. Email blacklist checker is a software tool that allows you to easily check email blacklists with just a few clicks. Using an email blacklist checker is faster and easier than manually checking individual blacklist email sites. 

List of Popular Email Blacklist Check Databases

For checking your domain listing in the blacklist database here are some popular ones you can look up your IP or domain name in:

Here are three public email blacklist checkers you should know about:

1. MXToolBox

MXToolBox is a blacklist checker that tests the IP address of a mail server against over 100 DNS based email blacklists. To use this, all you have to do is enter a server IP or domain name, and MXToolBox will display a table with each blacklist in its database and its response. If everything is alright and your mail address isn’t blacklisted, you will see around 100 blacklist checks with “OK” next to them.

You can then instruct MXToolBox to monitor your mail address and alert you if it ever gets blacklisted. As a free user, you have access to monitor one mail address and access troubleshooting information about backlist, email, DNS, & web issues. 

2. enables you to check the blacklist status of your mail server’s IP address on more than 100 DNS based blacklists. All you need to do is enter the IP address you want to check into the “Quick Blacklist Check” field and click the “Check This IP” button next to it. If your email isn’t blacklisted, you will see green “OK” labels next to all blacklists checked by


This is a comprehensive blacklist email address checker that has access to consulting over 120 different email blacklist databases. It allows you to perform FCrDNS and DNSBL lookups on IPv4/IPv6 addresses or domain names. It is completely free. 

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Types of Email Blacklist Services

There are two kinds of Email Blacklist services and they are available based on the service using it. 

  1. The third-party Email Blacklist Services

These are independent organizations that provide blacklists as a service to major email services such as Gmail, Yahoo, Email delivery services, Spam engines, and much more. They are more widely available and open for public usage, to freely check their listings manually.

  1. The Internal Email Blacklist Service

Although Gmail, Yahoo might use these third-party services to check to blacklist, they also have their own filters to update their version of blacklists. These internal blacklists are not so much as open to the public users to use without any verification.

Email Blacklist Removal

If you’ve found out that your email address has been blacklisted, know that it isn’t the end of the world. What you need to do is change what’s wrong and contact the spam list, telling them that the problem is now fixed.

Asides cleaning up your email list, another thing to do is scan your computer and other devices for malware and use an inbox cleaner to organize your inbox and remove all emails you don’t need. 


Seeking to know if your email has been blacklisted isn’t difficult because there are many free email blacklist checkers that you can use to instantly see if your email address has ended up on an email blacklist. Discovering that your email address has been blacklisted is the first step toward email blacklist removal.

To successfully remove a blacklisted email address from all email blacklists, you need to change what’s wrong and contact the owners of the corresponding email blacklists. You should also verify that your computer and your inbox are clean.

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