The Email Stack Scan a domain
← All free tools

Blocklist lookup

/blocklist

Check a domain or sending IP against the public blocklists in one place, and see how to get off any that list you.

Queried live from your browser through public DNS. A domain is resolved to its web and mail server addresses first. Nothing is stored.

What blocklists do

  1. What it is

    Blocklists (DNSBLs) are public lists of IP addresses recently seen sending spam, each run by an independent operator.

  2. Why it matters

    Receiving servers consult them before accepting a message. A listed IP is rejected or filtered before the content is even read.

  3. Without it

    Without checking, you find out you are listed when mail starts bouncing, usually days after the listing began.

What we check

  • Eight DNS blocklists that answer public resolvers: Barracuda, SpamCop, UCEPROTECT Level 1, PSBL, Mailspike, DroneBL, Spam Eating Monkey and s5h.net
  • For a domain, its A records ("web") and the A records of its MX hosts ("mail"), up to six addresses
  • Each address's reverse DNS (PTR), which several lists require before they will delist
  • The exact return code for any listing, since some lists encode the reason in it

Spamhaus ZEN and DBL, SURBL and URIBL refuse queries from public resolvers such as Cloudflare and Google, so a browser-based tool cannot check them. The results include direct links to their own lookup pages. SORBS shut down in 2024 and SpamRats returns errors to public resolvers, so neither is queried.

Common questions

I'm listed. What do I do?

Find the cause first: a compromised mailbox, a form being abused, a purchased list, a server relaying for anyone. Delisting without fixing the source gets you re-listed within days. Then use the delist link on the row; each list explains its own process, and most trap-based lists expire on their own once the hits stop.

The mail IPs shown aren't the ones I send from.

Correct: they are the domain's inbound MX hosts, which is all DNS can reveal. If you send through Google Workspace, Microsoft 365 or an email service provider, the outbound IPs belong to them. Find your sending IP in the Received: headers of a message you sent, and check that address directly.

Does a clean result mean my mail will land?

No. Gmail, Microsoft and Yahoo run private reputation systems that no public blocklist reflects. Clean here means public lists aren't the problem; authentication, content and engagement still are.

What is 127.0.0.2?

A test address every blocklist lists on purpose, so operators can verify that queries work. Check it here and you should see it listed almost everywhere.