Blog , 07 Apr 2021

How to Check Whether Your IP Address is Blocklisted

Steve Freegard,

Sr. Product Owner Abusix Intelligence

Email can be the lifeline of a business – a way to communicate with your customers and advertise your products straight to their inboxes. 

But what if that lifeline is suddenly cut off? 

This is called IP blocklisting (formerly known as IP blacklisting). It’s a method used by networks to block IP addresses they think are malicious or sending out spam.

According to Statista, roughly 55% of all email is now classified as spam, leading to a decreased public trust in email itself. 

It’s costly for businesses, too. Studies show spam costs businesses more than $20 billion annually and harms productivity. 

For all of these reasons, avoiding an IP blocklist should be at the top of your priority list.

Not only does staying off blocklists help your email deliverability, but it can also boost your team’s productivity and save your company money. 

This article is going to cover: 

What is an IP blocklist, and what does it mean for your business?

An IP blocklist is where a network blocks an IP address or domain name from sending emails to them because it’s suspected of sending out spam or malicious content. 

Landing on an IP blocklist doesn’t happen randomly. There are several ways you can end up on an IP blocklist, including: 

The reasons above may not be what normally first come to mind when you think about spam emails. But when you consider the whole idea of a blocklist is to stop suspected spam and malicious activity, like sending out emails without the receiver’s permission, the reasons behind getting put on a blocklist start to make sense. 

In any case, getting put on an IP blocklist never happens without evidence. Your messages will go through a process every time you send an email to see if they are legitimate or spam:

Image: Own Source

Warning signs that your IP is blocklisted

If your emails are being delivered to the recipients’ “Spam” folder or they bounce back and you get a message saying it couldn’t be delivered.  In some cases, it might say outright that you have been blocklisted and provide a clickable link to find out more information.

These can be a warning sign that you have been blocklisted, and you need to check and confirm it.  

How to check if you have been blocklisted

This process is easy and there are several websites available that can check your IP address or domain against lots of different blocklists and whitelists, such as DNSWL.

You can use several public sites (for free) to check if your IP address has been blocklisted. Tools like MXToolbox and check your IP or domain name against known blocklists to see if your site has been placed on one. 

If your IP/domain has been listed on one of Abusix’s blocklists, you can go ahead and go to Abusix’s lookup tool, which will allow you to check if your IP address has been placed on spam, policy, or authentication blocklists by simply typing in your IP, Domain, or Email address:

Source: Abusix Lookup Page

Once you hit search, Abusix runs your IP through several lists:

If your IP address is on one of these lists, the search will label it as “listed”:

Source: Abusix Lookup Page

You get more details on why your IP has been listed when clicking on each of the lists. Once you fixed the issue, you can hit the red button “Remove from list”, to get the process of delisting your IP going. You’ll be forwarded to, where you’ll have to set up a free account.

How to remove your IP address from a blocklist

Once your IP address is blocklisted, getting it delisted can be a time-consuming and difficult task but it doesn’t necessarily need to be.

Most blocklists allow you to submit a request to remove your address from the list, as long as you’ve fixed the issue that landed you on the blocklist in the first place. 
Here’s what that process looks like using Abusix. Once you sign-up (which you can do here), you will be taken to a dashboard that looks like this:

Source: Abusix Portal

After you search your IP or domain name, Abusix will highlight any of their lists that you are blocklisted on. To get your IP/domain removed, you need to click the red “Remove from list” button, and then, Abusix takes over:

Once your IP address has been removed, you should pivot to a long-term approach of avoiding being put on another blocklist in the future. 

How to avoid your IP address being blocklisted

Every blocklist has its own criteria an IP address needs to meet before being placed on it.

While some reasons are based on evidence or behavior, others focus on technical violations like incorrect or missing DNS records. 

Still, the most common ways for your IP to end up on a blocklist stems down to compromised accounts or servers and poor email practice.  If there’s evidence that your servers or accounts have been compromised or you don’t have good email collection policies in place, there’s a high chance your IP will be blocklisted. 

Technical blocklists often come down to issues with your mail server configuration or DNS configuration and are harder to spot for those without a technical eye.

The good news is that there are some best practices you can follow to avoid IP blocklists from happening. Make sure that you: 

Is your IP/Domain blocklisted on our lists and you want to request a delisting? Please go to our look-up service page and follow the instructions there.

Are you running your own mail servers and would like to use Abusix’s blocklist as an additional layer of defense to protect our users from spam, malware and other email-related threats? Start your free trial today to see what our suite of blocklists can do for you.

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