Listed on Spamhaus SBL
Your sending IP is on the Spamhaus Blocklist (SBL). Major mail receivers will reject your mail outright.
Most of the global email infrastructure will refuse your mail entirely while you're on SBL. Not Junk — rejected. Your users will see bounces, not quarantined messages. Fix this before anything else.
What causes it
- You sent spam. Even one bulk mailing to a purchased list can get you listed. Spamhaus's spam traps are everywhere.
- Your server got compromised. A WordPress plugin, exposed webmail, or weak SMTP password lets attackers relay spam through your IP.
- A customer on your shared IP sent spam. If you're on shared infrastructure, one bad neighbor can list the whole range.
- Snowshoe spamming on your netblock. Spamhaus sometimes lists entire /24s when they see sustained abuse from that range.
How to fix it
Step 1: Confirm your listing
Visit check.spamhaus.org and enter your IP. It'll show the specific SBL record and reason.
Step 2: Fix the underlying cause
Rotate every password on the compromised server. Patch your CMS and plugins. Audit outbound mail logs for unexpected sends. Disable open relays. Close port 25 to anonymous SMTP. If a customer was the source, suspend their sending privileges.
Step 3: Request removal
In the Spamhaus check result, click "Request Removal." Describe the cause and the fix specifically. "Fixed the compromised server" is not enough. Describe what you changed, when, and how you'll prevent recurrence. Expect a response in 24-72 hours.
Step 4: Rebuild reputation
After delisting, Gmail and M365 still remember the past abuse. Ramp sending volume gradually over 2-4 weeks. Monitor your Postmaster Tools dashboards. Consider moving to a dedicated, warm-up-friendly service.
Fixed it? Run a fresh test to confirm.
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