How to check if your domain or mail IP is blacklisted

What it is

A DNS blacklist (DNSBL, also called an RBL or blocklist) is a published list of domains and IP addresses known for sending spam. Receiving mail servers check incoming mail against these lists and reject or junk anything from a listed source.

There are two kinds: domain lists (like Spamhaus DBL) that flag the domain itself, and IP lists (like Spamhaus ZEN, SpamCop, SpamRats) that flag the sending mail server's IP address.

Being listed is often not your fault — a shared hosting IP, a compromised account, a new IP with no reputation, or a forwarding loop can all get an IP listed.

Why it matters

Blacklisting is one of the most damaging and least visible deliverability problems: your mail doesn't bounce loudly, it just quietly lands in spam or is dropped, and you find out when a client says "I never got your email."

For agencies and MSPs managing many client domains, a blacklisting on one client's shared IP can affect everyone on that server — so checking regularly matters.

Getting delisted is usually quick once you find the listing and fix the underlying cause, but you can't fix what you don't know about.

How to set it up

1. 1Identify the IPs that actually send your mail: your domain's A record and, more importantly, the IPs behind your MX / outbound mail server.
2. 2Check the domain against domain blocklists (Spamhaus DBL) and each sending IP against the major IP blocklists (Spamhaus ZEN, SpamCop, SpamRats, PSBL, Mailspike, UCEPROTECT, s5h) — our free checker does all 8 at once.
3. 3If you're listed, open the blocklist's lookup page for the specific listing — it usually states the reason (spam seen, compromised host, poor reputation) and the delisting process.
4. 4Fix the root cause first: secure any compromised mailbox, stop the spam source, tighten SPF/DKIM/DMARC, and warm a new IP gradually. Delisting before fixing the cause just gets you relisted.
5. 5Request delisting through the blocklist's form. Reputable lists (Spamhaus, SpamCop) remove you quickly once the cause is resolved; low-quality lists often expire on their own.

Common problems

How do I know which blacklist I'm on?

Run your domain and mail IPs through a multi-list checker. Our free blacklist checker resolves your A + MX IPs and checks them against 8 major lists in one go, telling you exactly which list flagged which IP.

My domain is fine but my IP is listed — why?

Domain and IP reputation are separate. Shared hosting or a shared outbound relay means someone else's behaviour on the same IP can get it listed, even if your domain is clean. This is common on budget hosts.

How do I get removed from a blacklist?

Find the specific listing, fix the underlying cause (compromised account, open relay, spam), then use that list's delisting request form. Don't request delisting before fixing the cause — you'll just be relisted, and repeated requests can slow removal.

How often should I check?

For a single domain, whenever deliverability drops. For agencies watching many client domains, continuously — a listing can appear any day. DomainHealthPro's paid monitoring re-checks every domain daily and alerts you the moment one is listed.

More guides