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My IP Address

Is this IP on a blocklist?

Checked against more than fifty DNSBLs, live, with a delisting link for every hit.

Runs on our server; the query is not stored.

What a DNSBL is#

A DNS-based blocklist publishes a list of addresses through DNS itself. To check one, a mail server reverses the address, adds the list's domain, and looks it up: for 203.0.113.42 and a list at dnsbl.example, it asks for 42.113.0.203.dnsbl.example. An answer in the 127.0.0.x range means listed, and the last number says why. "No such name" means not listed. It is the same reversed form that reverse DNS uses, and it is fast enough to run on every incoming message.

This tool asks around sixty lists in parallel and shows each answer. Results are kept for up to fifteen minutes, so a repeat check of the same address within that time shows the earlier answer. After you have fixed something and asked a list to remove you, wait and check again later.

Reading the statuses#

What each status means
StatusMeaning
ListedThe list has flagged this address, and gives a reason code and a delisting link
PolicyA range the list flags by category, such as residential dynamic addresses that should not send mail directly. Not a report of abuse
CleanThe list answered and does not include the address
No answerThe list did not reply in time. That is not evidence either way

If an address is listed#

  1. Find the cause before asking for removal. A compromised device, an open mail relay, or a shared address that someone else abused. Delisting without fixing it gets you listed again within days.
  2. Use the list's own delisting link. Each list has its own process, and some remove entries automatically after a period.
  3. For policy listings on a home connection, do not try to delist. Send mail through your ISP's or a provider's relay instead. Residential ranges are listed on purpose.
  4. Behind shared addresses, you inherit the neighbours' reputation. See what NAT and CGNAT are.

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