How to Check if Email Addresses Are at Blocklisted Domains

To check whether email addresses are at blocklisted domains, ask the public domain blocklists about the domain after the @ in each address. The bulk email domain blocklist checker does that for a pasted list or CSV and gives every address a row: Listed on a blocklist, Not listed or Unclear. Up to 50 unique domains per ten minutes, 250 after a free Google sign-in.

It asks two lists only, so Not listed means not listed there, and it checks the domain, not the mailbox.

Which lists, and why only two

The checker asks URIBL and the NordSpam DBL, public DNS blocklists of the kind RFC 5782 describes. Each query comes with a test entry, so a list that refused the query or went silent is reported as Unclear and never as clean. Spamhaus DBL and SURBL are not asked, because their free terms exclude commercial sites. For those, use the lists' own lookup pages.

When to bother

Most lists have a handful of listed domains at most. The check is worth running on purchased lists, scraped lists and old exports, where addresses at spam-linked domains cluster. It is a screen before a send, in the same spirit as checking whether your own domain is on a blacklist, pointed at the recipients instead.

The by-hand way

1. Take the domain after the @, for example acme.example.
2. Query each list's lookup page, or its DNS zone, for that domain.
3. Note whether it is listed and which list says so.
4. Repeat for every unique domain.

Step 1: paste the addresses

Paste addresses one per line, or upload a CSV. Only the unique domains, never the mailbox names, are sent as DNS queries to the lists, 10 a request. Nothing is sent to the domains.

Step 2: run the check

Press Check domain blocklists. No mail is sent and no mail server is contacted.

Step 3: read the result

Result	What it means
Listed on a blocklist	A list named the domain; the row names the list
Not listed	None of the lists queried names the domain
Unclear	A list gave no trustworthy answer; the row names it

The CSV adds the list names and the domain actually looked up. Listed addresses are left out of the list handed on to the mailbox check.

What this check cannot do

• It checks the domain, not the mailbox. A listing is about the domain, not the person.
• Only two lists are asked. Not listed here does not mean not listed anywhere, and a new domain may not be listed yet.
• A free provider such as gmail.com is one domain, so its result says nothing about a single mailbox.
• 50 unique domains per ten minutes without an account, 250 signed in; the limit is counted over ten minutes, not per run.

To check domains without the addresses, use the bulk domain blacklist checker; for the mail servers' IP addresses, see checking whether MX servers are blacklisted. For how the three kinds of reputation differ, read domain vs IP vs mailbox reputation.

Next: the mailboxes

Use the verify page on what remains: the first 100 checks are free with a Google sign-in, no card.

Try it now

Paste your list into the bulk email domain blocklist checker.