IP blacklist check
Query ten major DNS blocklists — Spamhaus, SpamCop, Barracuda, SORBS and others — to see whether a mail server IP has been listed.
What a listing means
DNS blocklists are consulted by receiving mail servers in real time. A listing on a widely used list such as Spamhaus ZEN can stop most of your outbound email dead, and you will often notice only through bounce messages.
Common reasons for a listing
- A compromised mailbox or web form being used to relay spam.
- A shared hosting IP where somebody else on the machine misbehaved.
- Sending to a stale list with a high bounce or complaint rate.
- Missing reverse DNS or an obviously dynamic-looking hostname.
- A newly allocated IP inheriting the previous tenant's reputation.
Getting delisted
Fix the cause first — a delisting request on an unfixed server gets you relisted within days, sometimes with a longer penalty. Then use each list's own removal form; most major lists offer self-service delisting and act within hours. Do not pay a third party for removal: no legitimate list charges.
Not all lists carry equal weight
Spamhaus, SpamCop and Barracuda are used at scale and matter. Some smaller or more aggressive lists are barely consulted, and a listing there may have no practical effect on delivery. Judge by whether your mail is actually bouncing, and read the reason text in the bounce.
FAQ
Can I check a domain instead of an IP?
Enter a domain and we resolve it first, then check the address it points to. For email problems, check the IP your mail actually leaves from — it is often not the same as your website.
How long does a listing last?
From a few hours to several weeks, depending on the list and the behaviour. Most expire automatically once the source stops.
My IP is clean but mail still fails
Check SPF, DKIM, DMARC and reverse DNS, and read the exact bounce text — large providers apply their own internal reputation systems that no public list reflects.
Related reading
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Open port checker
Which TCP ports answer from the outside.
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