Email Blacklists: Ways to Check, Avoid, and Get rid of it

Email marketing is an important part of any business; it can be frustrating how some of the emails do not even make it to the recipient. 

Sometimes, even having a single issue ends up mistaking and negatively affecting your email deliverability. 

It can be different issues, maybe a bad email address or full inbox, or it might be a typo; there are chances of getting on a blacklist. This prevents the email from reaching its recipient. 

To understand what can help, here is a quick guide for getting better knowledge of email blacklists. 

What To Know About Email Blacklist? 

Before you know how to deal with email blacklists, the first thing you need to understand is what email blacklists are. 

The email backlist is the real-time list that is identified by the domains or IP addresses known to send the spamming emails. 

Email service providers or ESP, free mailbox providers, internet service providers or ISP, anti-spam vendors, etc. use the blacklist in order to stop such emails from entering the system. 

When you get flagged by the blacklist operators, this adds up to the list and blocks the content; it also prevents the email from 

What Are The Types Of Backlist Services?

Well, there are two kinds of email blacklist services which depend on how they are available to the service for using it; here is what you can know. 

The Third-Party Email Blacklist Service 

You get third-party email blacklist services; these are independent organizations that provide the blacklist services as a service to email services, including email delivery service, Gmail, Yahoo, spam engines, etc. 

These are more ideally available and open for usage to the public; here, you can check the listing manually. 

third party email blacklist services

The Internal Email Blacklist Service 

Yahoo and Gmail might use a third-party service for checking the blacklist. 

But they also know about using the filters for updating the version of the blacklist. These internal blacklists are not open to the public for use without any verification. 

What Are The Email Blacklist Categories?

An email blacklist is divided into two basic categories depending on what identifier is used for identifying the source of a spammer. 

It includes : 

IP Blacklist 

Every server has its IP address; this defines the location on the internet. 

As for emails, these are sent from the email delivery service to the receiving service, such as Gmail. 

The public IP address of servers that are known for sending spam emails, infected with botnets, or servers that are acting as open pages are added to the IP blacklist.

Domain Blacklist 

Each email that you send has a domain associated with it; this is called the email sending domain. 

It can be seen from the address, return address, and DKIM signing domain. 

If your emails are sent by any of these domains, they will be considered spam emails depending on their spending habits as well as history regarding email sending. 

Who Influences Your Email Blacklist?

You might be sending extremely good quality in your emails, but even small mistakes can lead to the domain being blacklisted. 

For example, if you have a list that does not have opt-in and has been procured from an external source, there is a high chance your list might contain the spam trap or honey pot email address. 

Hitting spam traps to email addresses leads to imitating a blacklist of sending the domain and IP address on multiple services of DNSBL.

Anti-spam vendors, ISP, MSPs, or normal recipient users of the email can influence your blacklisting of the domain email sender or the IP address. 

MSP Or Mail Service Providers 

MSPs are email services that provide email inboxes such as Outlook, Gmail, Yahoo mail, Zoho mail, etc. 

These services keep looking for emails that are suspicious in behavior and will spare no one if they are able to detect the spam.  

They also use multiple resources and filter spam emails such as : 

  • Anti-spam engines
  • Third-party email blacklist 
  • Domain reputation list 
  • Email Policies 

This helps in defining how they are going to behave against types of certain kinds of emails. 

The Email Recipient 

The email recipient is passive information when it comes to email blacklisting. The open SMTP protocol allows sending any kind of email. 

Here you don’t get the protocol level check or restriction; even though there is a lot of anti-spam software that you get in the industry, it’s tough to catch and hold all kinds of spam. 

In order to avoid spam, most MSPs offer the Report as a spam button; this is open polling. So when there are enough flags against the email, then the domain will end up getting backlisted. 

Spam Traps Or Honey Pot 

Well, this type of email address seems like an ordinary email address. However, it is primarily owned by the MSPs and anti-spam agencies. 

They distribute these email addresses as traps across the internet for checking if there is someone who is ending the non-opt-in users. 

Most of the third-party email or harvest listed contains some of the email addresses which are spam traps. 

So when you hit on every single trap, this influences and real-time blacklists the sender IP and domain address. 

There are different types of spam traps that you might get, but these are divided into two categories. 

Classic Spam Traps 

The email ids here are ones that are created primarily to blacklist anyone who is sending emails to such email IDs. 

Recycled Spam Traps 

These email ids are abandoned or unused for such a long time or might have a closed account; mostly, ISP uses such email addresses. 

These are less strict on adding but will damage the domain’s reputation. 

How You Can Get Backlists?

To understand how companies and individuals get their IP blacklisted, it’s important to find the reasons behind it. 

You can get blacklisted if your email marketing campaigns are receiving high spam complaints or when they are sending to the email list which is bad. 

things get you on blacklist

However, there are different things that lead to your IP getting blacklisted. It includes : 

Spam Content 

If the recipient is marketing the emails as spam, then the ISP will assume your email content is bad. 

So if the emails are receiving complaints regarding the content, the chances are high that IP addresses will be added to the blacklist. 

Bad List Or Email Address 

When your email address is having a high bounce address, then it indicates that your list is not having a healthy email address. 

It’s either bought email or contains bad email addresses. Even some of the blacklists use the spam trap to locate the spamming IP address. 

With the help of spam traps, the email address that has no owner is found publicly and used for increasing the list. 

Having No Unsubscribe Button

Well, according to GDPR, it is mandatory that your email should have the unsubscribe button. Also it should be on every single email you are sending to your recipient. 

When your email doesn’t have it, there are high chances that people will mark such emails as spam since you are not respecting the decision of your recipient as to whether they like to receive the email or not. 

Low Open Rates 

If your email has a very low amount of open rates, this can also indicate that you might have an email list rented or bought. 

However, in both cases, there is a chance of your IP getting blacklisted since the ESP might think that your emails are spam. 

How does Email Blacklist work?

To understand how this whole email blacklist works, here is what can help you. 

Recycled Spam Traps 

These are email addresses that were once valid but have been dormant for a very long time as they haven’t been engaged with any email. 

If you are sending messages to these addresses, which are mostly refused or bounced by the receiving server for a year or more, then that. These can be the spam trap addresses that are required to avoid. 

Typo Traps 

Another one is typo traps; these email addresses end up usually on the recipient list because of an error. 

Typing something like [email protected] instead of typing [email protected] is quite the same as recycled spam taps, as such addresses are never going to click on messages or open the emails they are receiving. 

This makes the anti-abuse community believe that sending emails in excessive amounts to such emails shows that you have poor list acquisition practices and bad hygiene.

Pristine Traps 

Well, these email addresses and domains have recently been used for actively signing up for receiving email. 

Pristine traps are mostly common and end up in email lists when you have sender purchase, scrape or rent addresses.

How To Avoid Getting Backlisting?

To make sure you are not getting blacklisted in the first place, you need to consider all the ways that can help because it’s much better than getting an address removed from the list once you are being flagged. 

Aside from making sure that you are not falling into the trap, here are some of the ways that can prevent this. 

ways avoiding getting on blacklist

Maintaining The Opt-In List 

In order to avoid getting blacklisted, make sure you are never emailing anyone without their permission. 

Make sure you have the opt-in; this is a list it may take some time to grow. However, this helps in getting much better and higher quality. And also, you get lesser chances of getting flagged.

Remove Addresses Which Have Higher Bounce 

If you are not getting a notice about an email, or it has bounced or is noted as undelivered, makes sure you are removing all of these addresses from the list. 

The more you send emails to the types of such addresses, this will end up getting blacklisted. 

Check Your Contact For The Typos

To avoid the chances of blacklisting, you need to set aside some time to make sure you are scrolling through the contact list. 

Invest your time in putting the correct address and do it the right way. It could take time, but it’s worth it; this will help you in assuring that you are not sending emails to the wrong addresses. 

Perform Your Routine Maintenance 

Do set time to perform the routine maintenance; this is important as it will ensure your list does not contain any bounced emails, spam accounts, or incorrect emails. 

This also ensures that you have a hygienic email list and improve your email campaign. 

Don’t Buy The Emails 

This is important for understanding that an email list is crucial for you.  It takes time and effort to create an email list that can be effective for you. 

However, buying an email list not just puts your campaign at risk but also threatens the reputation and blacklists the IP address.

Make Sure To Verify Email Address

When you are sending the email address, you should always verify it and the content of each email. 

So this will help you in getting the legit send. You can consider using tools that can verify the email address. 

What Are The Critical Email Blacklists To Care About?

There are so many email blacklists, and it’s everywhere; there are chances that your server IP address might be listed in one of them. 

Many email blacklists try to impress by offering a long list of DNS-based real-time blacklists or DNSRBL. 

While some are smaller kits that might be useful, however, there are only 8 important email blacklists you need to pay attention to. 

It includes : 

Composite Blocking List 

CBL is a list that is managed by the Spamhaus; it’s the only backlist IPS that has shown the exhibit of malicious behavior such as open proxies, dictionary attacks, spambots, or something similar to that. 

Many hackers run the dictionary or open it after they do the web sites hacking. 

If they end up hitting the servers which are monitored by CBI , the IP address of the server will be added to the list. 

Spamhaus Block List 

SBL is the Spamhaus list which includes the email which is from the spam operations, services, and known sources. 

They also use spam traps; these email addresses do not belong to the actual users. 

If your website or server is hacked, the spammers often flow with emails which are around 10 000 emails in the system. If this hits the spamtrap of SBL, then this can end up listing the server. 

XBL Exploits Block List 

The XBL mainly lists all the IP addresses which are hijacked. At the same time, these typically include PCs instead of not SERVERS. 

However, you can also get the servers listed; if a pc is hacked, this might use the server as an SMTP gateway, or the server is used as a getaway for spamming. 


Spam cop is used primarily as spam traps and spam reports for generating a reputation score.

If you are noticing the score drops way too low, the IP might be included in the list as well. 

However, they balance the spam reports along with reputation points for trying to avoid just one or more reports which are triggering lists. 

Passive Spam Block List 

This one is called PSBL; it’s an easy-on and easy-off backlist. They are not the traditional testing and scoring. However, it relies on spam traps.

If the server is email entering the spam trap, the server’s IP blacklist. This can easily be removed by making the request.  


Well, this one runs on a number of lists, including ivmURI ( domain-based, ivmSIP /24 ( network-based), and ivmSIP ( IP based).

The ivmSIP is actually based on IP based blacklist, which mainly lists IPs along with high spam percentage. 

If you have the server in this list here, you likely have to make the email compromise. 

Whereas ivmSIP/24 is a network-based one designed for targeting the spammers spreading the email over large numbers of snowshoe spammers or IPS. 


This one is a backlit resource that powers the barracuda anti-spam appliances. 

They make the list that is available for others to use via this.  Many systems which are web hosting, such as cPanel, use the list by default. 

Most IP addresses are listed as sending spam, which is directly for the detectors from the barracuda reputation system.


Senderscore is a return path for the sender reputation system.  This is used for a large number of small service providers, email marketing service providers, corporate email systems, and others. 

If you are scoring to their system, which drops lower than 85, this causes delivery issues. Instead of an email blacklist, non-blocking is directly done depending on the sender score. 

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