IP blacklist check: is your server blacklisted?

A blocklist (or blacklist) is a list of IP addresses or domains that have sent spam or are infected. Mail servers look up every incoming connection on these lists and reject or filter email from listed addresses.

First fix the cause: an infected computer, a hacked website or mailbox, or a form that sends spam. Then use the removal page of the list named in the result. Most lists remove an address on request or by themselves after a few days without new spam.

The PBL lists address ranges that internet providers give to home users. It is not a spam listing: it just says these addresses should send email through a mail server, not directly. It only matters if you run a mail server on that connection.

Some lists, including Spamhaus, refuse lookups that come from shared hosting or large public DNS servers. In that case we do not know the result, so we say so instead of calling the address clean.

These levels list whole networks or hosting providers when many of their addresses send spam, so an honest server can be listed because of its neighbours. Few mail servers use them.