How to deal with email blacklists


In an ideal world, all emails go straight to the recipient’s inbox.

The truth is, some of them don’t get delivered because the sender’s IP address or domain may have been blacklisted.

Here’s a quick look at what email blacklists are, how you can check if your IP address/domain has been blacklisted, and how to request blacklist removal.

What is an email blacklist

An email blacklist is a database of domains and IP addresses blocked as suspected of spamming. Its goal is to cut down on the number of unwanted or spam emails delivered to ESP users.

There are plenty of email blacklists out there, but major ones are run by either email service providers (Gmail, Outlook) or cloud email security companies (Cloudflare, Mimecast, Barracuda).

Why you might get blacklisted

Various ESPs and blacklist vendors may have different definitions of spam activity. Yet, there are a few typical reasons your IP address or domain can end up on a blacklist:

  • Falling into the spam trap
  • Getting flagged as spam by your recipients 
  • Not verifying your prospects’ email addresses, which leads to a high bounce rate 
  • Sending too many emails within a short period of time

How to check if you’re on a blacklist

Being blacklisted will most likely affect your ability to get into the recipient’s inbox, damaging your marketing performance.

Doing an occasional blacklist check is a good idea, especially if you get a lot of undelivered emails with a delivery error like this: 550 5.7.511 Access denied, banned sender[].

You can directly visit a website of a blacklist provider and use their internal lookup tools, or you can use blacklist check tools that will test your IP address or domain against hundreds of email blacklists.

Below are some of the most well-known blacklists. Follow these URLs to find out whether your IP or domain is blacklisted there:

A quick check for multiple blacklists at once is possible with MXToolBox or MultiRBL. Commonly, you’ll just need to enter your IP address or domain name to run a check.

What to do if your IP address or domain is on a blacklist

Being on a blacklist is not as bad as it sounds. You can still take the necessary action to fix this:

1. Request blacklist removal

If you’re on a blacklist at any email service or blacklist provider, you can send them a request to delist you.

Typically, you’ll have to open the removal page and apply for delisting by filling out an online form or sending an email.

  • For example, to get removed from the Barracuda blacklist, you should follow this URL and submit the online removal request.

On the Removal request page, Barracuda asks you to enter your email server’s IP address, your contact email address and your phone number. In the Reason for removal area, briefly outline the issue and provide a list of steps you’ve taken to prevent it in the future.

The list of steps is usually standard, e.g., “I’ve configured SPF and DKIM in my DNS” or “Now I use double-opt in scenario to get clear consent from my recipients”.

2. Take steps to prevent blacklisting in the future

To minimize the risk of being flagged, prevent your IP or domain from being blacklisted, and keep a good email drip campaign performance, you should follow email marketing best practices:

  • Ask your recipients to opt-in
    If you email someone without their permission, you will more likely than not get marked as spam. You can reduce the number of spam complaints by asking for clear consent from your prospects. 
  • Verify your email list and remove inactive subscribers
    Use Email Verifier to check every email address for validity before starting your outreach. Delete those emails that show no interest or engagement from your list. 
  • Remove bounced emails
    If you get a notification that an email has bounced or is undeliverable, remove the email address from your list and keep your bounce rate low. 
  • Avoid spam words
    Spam filters are usually triggered when a certain word or phrase is used in an email body or subject line. Here’s our list of spam words to avoid
  • Check your sender reputation
    Email service providers use a sender score to determine if you’re a good sender. Use online tools like Sender Score or Cisco Talos to monitor your sender reputation regularly.


It takes a lot of time and effort to build an effective and safe email marketing campaign, but the effort is worth it to make your outreach successful.

Take a look at our guide on email deliverability and never end up on a blacklist in the first place.

Put everything you’ve learned into practice and give it a try with Email Drip Campaigns

Good luck!

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