How to get your domain off the Spamhaus blocklist

Usually a bounce message. You send an email, and a few seconds later a reply comes back saying it wasn’t delivered, with something like this in it:

554 5.7.1 Service unavailable; Client host [203.0.113.25] blocked using zen.spamhaus.org

The exact wording depends on who refused the email, but the word Spamhaus is the giveaway. The numbers in brackets are the server address that was refused. Sometimes there’s no bounce at all and customers just say your emails stopped arriving.

Most small businesses send email through Microsoft 365, Google Workspace or another email provider. Their servers send email for thousands of businesses, so when one of them is listed, it usually isn’t about you, and only the provider can get it removed.

1. 1
   Find the bounce message (the email that came back saying your message wasn’t delivered). It names the list and usually shows the server address that was refused.
2. 2
   If you send through Microsoft 365, Google Workspace or another provider, forward that bounce to their support. Say which customer it was going to and when. They handle the removal.
3. 3
   If your email goes out from your own server or your web host, the steps below are yours to follow, or your IT person’s.

1. 1
   Go to check.spamhaus.org and type in your web address (for example yourbusiness.com).
2. 2
   Then look up the server address from the bounce message, if it showed one. It’s a string of numbers like 203.0.113.25.
3. 3
   Read the reason it gives. Each result names the list and says why it was listed. That reason tells you what to fix.

Spamhaus runs several lists. The lookup tells you which one, and each needs something different:

Your web address is listed (Spamhaus calls this the DBL). Email that mentions or links to your website gets refused, whoever sends it. Most of these listings end on their own once the activity that caused them stops.

A server was seen sending unwanted email (the CSS list). These normally end three days after the last problem email, but come straight back if it keeps happening.

A server or device looks like it was taken over (the XBL list). Something on that network, often a website, plugin or computer, is being used by someone else to send email.

The server belongs to a known spam operation (the SBL list). Only the company that owns the network can deal with these, so this one goes to your email provider or web host.

It’s an ordinary home or office internet address (the PBL list). This one is normal and isn’t a black mark. It only causes trouble when an email program sends directly instead of signing in to your email provider. Fix the email program’s settings; you don’t need removal.

We can’t tell from the outside why a business was listed, only that it was. The list’s own lookup shows the real reason. Common causes: people marking your email as spam (this often follows cold or bulk email), links to your website appearing in email that got reported, or someone else getting into one of your mailboxes or your website.

1. 1
   Fix the reason first. If you ask before the problem stops, the listing comes back, and Spamhaus limits how often you can remove yourself.
2. 2
   Go back to check.spamhaus.org, look up the same web or server address, and follow the removal steps shown next to the listing.
3. 3
   Use an email address at your own business, not Gmail, Hotmail or Yahoo. Spamhaus throws out some removal requests from free addresses.
4. 4
   Wait a few minutes, then test. Spamhaus says approved removals take effect within minutes, though some email systems take up to 24 hours to catch up.

Email only people who asked to hear from you, keep your website and its plugins up to date, and send newsletters through a newsletter service rather than your everyday mailbox.

Want to know the day it happens instead of finding out from a customer? SenderFix Monitor keeps checking the main spam lists for your business and emails you, in plain English, if you show up on one.