Email Blacklists: How to Check and Get Delisted

Being on a blacklist can silently stop your emails reaching anyone. Here's how to find out and fix it.

What is an email blacklist?

Email blacklists (also called blocklists or RBLs — Real-time Blackhole Lists) are databases of IP addresses and domains that have been identified as sources of spam or malicious email. Receiving mail servers query these blacklists to help decide whether to accept, reject, or flag an incoming email.

There are hundreds of blacklists operated by different organisations. The ones that actually matter for deliverability are a relatively short list of authoritative registries that major inbox providers and mail server administrators trust.

The blacklists that actually matter

Not all blacklists are created equal. Being listed on an obscure registry that few servers query is low impact. Being listed on Spamhaus — which is consulted by virtually every major inbox provider — is critical.

The most impactful blacklists for email deliverability are: Spamhaus (SBL, XBL, DBL — the most widely used), Barracuda Reputation Block List (BRBL), Invaluement (ivmSIP, ivmURI), Sorbs, and SpamCop. Being on Spamhaus in particular will result in near-complete delivery failure to Gmail, Outlook, and Yahoo.

Key blacklists to monitor: Spamhaus SBL → spam source IPs (most impactful) Spamhaus DBL → domain blacklist Spamhaus XBL → exploited/malware IPs Barracuda BRBL → widely used by enterprise mail servers Invaluement → highly accurate, less aggressive Sorbs → moderate impact SpamCop → auto-populates, can have false positives

How to check if you're blacklisted

The fastest check: MXToolbox Blacklist Lookup (mxtoolbox.com/blacklists.aspx) checks your domain or IP against 100+ blacklists simultaneously and shows which ones you're listed on. Run this check for both your sending domain and your sending IP address.

For routine monitoring, check monthly as a minimum — and immediately whenever you notice a deliverability drop (sudden reply rate decline, email bounce rate spike, or Google Postmaster showing domain reputation dropping).

  • Check both your domain AND your sending IP — you can be blacklisted on either.
  • MXToolbox shows green/red status for each blacklist with direct links to the listing details.
  • Set up a monitoring service (MXToolbox has paid alerts) if you're sending high volume regularly.

How to get delisted

Each blacklist has its own delisting process. The general pattern: understand why you were listed (look at the listing reason on the blacklist's website), fix the underlying problem (clean your list, stop the spam complaints, fix the compromised server), submit a delisting request through the blacklist's web form, and wait.

Spamhaus delisting: go to spamhaus.org, find your listing, read the reason, fix the issue, and submit the form. Spamhaus typically processes requests within 24–48 hours if the problem is genuinely resolved. Barracuda delisting: go to barracudacentral.org/lookups, find your IP, and submit a removal request. Barracuda is generally straightforward for legitimate senders.

  • Fix the root cause before requesting delisting — if you delist without fixing, you'll be relisted within days.
  • Most blacklists will not delist if they detect you're still sending spammy emails.
  • Some listings expire automatically after a period of clean sending — check whether the listing is time-limited.

Preventing blacklisting

The best defence is proactive. The habits that prevent blacklisting: keep bounce rates under 2%, keep spam complaint rates under 0.08%, only send to opted-in or well-targeted prospects, never buy email lists, warm up new domains properly, and monitor your sending domains monthly with MXToolbox.

If you're using a managed provider like Google Workspace, your sending IP is Google's — which is almost never blacklisted. Your domain can still be blacklisted on the Spamhaus DBL (domain blacklist) if you accumulate enough spam complaints. Your domain reputation is always your responsibility.

  • Monthly MXToolbox checks take 2 minutes and can save weeks of deliverability recovery time.
  • A sudden bounce rate spike is often the first sign of a blacklisting — investigate immediately.
  • If you've been listed on Spamhaus, don't try to work around it — fix the root cause and delist properly.