IP & Domain Blacklist Check

A DNSBL is a list of IPs or domains seen sending spam, infected with malware, or otherwise abused. Receiving mail servers and spam filters check these lists, then reject mail from a listed IP or mark it as spam.

Find the cause first: a hacked mail account, a compromised website script, or an infected device. Once it is fixed, open the check/delist link on that blacklist's row and request removal. Some lists, like SpamCop and PSBL, drop a listing on their own once the spam stops.

Spamhaus, SURBL, and URIBL refuse queries that come through public resolvers or go over their free usage limits, and some other lists occasionally do not answer. ipku.in tests every list with its test entry first; when even that fails, the result is marked unknown so it is never mistaken for clean.

The PBL (Policy Block List) is not a spam listing. It holds dynamic and customer IPs that their ISP says should not send mail directly. That is normal for a home IP, but a mail server should use an IP that is not on the PBL.

Yes. curl 'ipku.in/en/tools/blacklist-check?q=203.0.113.9' returns each blacklist's result as plain text, and /api/blacklist/203.0.113.9 returns JSON.