Blocklist check

What a blocklist check tells you

Mail servers ask DNS blocklists (DNSBLs, also called RBLs or blacklists) about every connection: "is this sending address known for spam?" A listed address can see its mail rejected or sent to junk. Domain blocklists (URIBLs) do the same for domains that appear in links and sender addresses.

Enter an IP address to check it against the IP lists. Enter a domain or email address to check the domain against the domain lists, and its mail servers' and website's addresses against the IP lists.

How the results stay honest

• Each list is asked through its own nameservers. Spamhaus, SURBL and URIBL refuse queries that come through public resolvers such as Google or Cloudflare, which makes many online checkers report "not listed" when the list simply refused to answer.
• Before a "not listed" counts, each list must list its own test entry. A list that refuses us, has gone offline or answers strangely is shown as "not verified" instead of clean.
• Listings show the list's return code, what it means (for example Spamhaus SBL, XBL or PBL), the explanation the list publishes, and a link to look it up and request removal.

If you are listed

• Find and fix the cause first: a compromised account or machine, an open relay, a form that sends mail to anyone, or a sudden burst of mail to old addresses. Removal requests are refused while the problem continues.
• Many listings expire on their own once the spam stops: SpamCop after about a day, UCEPROTECT Level 1 after a week.
• A Spamhaus PBL listing on its own isn't a spam accusation. It marks home and dynamic addresses, which should send mail through their provider's mail server rather than straight to the internet.
• Set up SPF, DKIM and DMARC, reverse DNS that matches your mail server's name, and a steady sending pattern. These matter as much as staying off blocklists.

Questions

Why does another site say I am listed when this one says I am not?

Some sites check dozens of small or abandoned lists that hardly any mail server uses, or count lists that refused their query as listings. This check uses widely used lists and only reports "not listed" when a list has proved it answers us.

What does "not verified" mean?

The list didn't confirm its own test entry: it refused our query, didn't answer in time, or behaved unexpectedly. Its answer for your address can't be trusted either way, so it isn't counted as clean. Check that list on its own website.

How do I get off a blacklist?

Stop the cause, then use the "Look up and request removal" link for each listing. Most lists have a self-service removal form; some, like SpamCop, delist automatically once reports stop.

Does a blocklist listing affect my website?

Usually not. Blocklists are used by mail servers. A domain on Spamhaus DBL or SURBL can, however, make mail that mentions your domain land in spam, and some security filters block links to listed domains.