Email blacklist check

Check a domain against three domain blocklists and its mail servers' addresses against three IP blocklists.

An email blacklist check asks public blocklists whether they list your domain or your mail servers’ IP addresses. This one checks the domain on Spamhaus DBL, SURBL and URIBL, and your MX hosts’ IPv4 addresses on Spamhaus ZEN, SpamCop and PSBL. A list that refuses our query shows as could not check, never as clean, because Spamhaus and others refuse queries from public and cloud resolvers.

Last verified October 18, 2026. The sources named on this page were read that day.

Sample report. `kestrel-labs.example` is a made-up domain

Its records are written to show each kind of finding. Check your own domain above.

Could not check

Not listed on the 14 queries that answered. Spamhaus DBL could not be checked from our server.

Blocklist results for kestrel-labs.example
List	Checked	Result
Spamhaus DBL	`kestrel-labs.example`	Could not check Spamhaus refused the query from our resolver.
SURBL	`kestrel-labs.example`	Not listed
URIBL	`kestrel-labs.example`	Not listed
Spamhaus ZEN	`64.233.178.26`	Not listed
SpamCop	`64.233.178.26`	Not listed
PSBL	`64.233.178.26`	Not listed
Spamhaus ZEN	`74.125.197.26`	Not listed
SpamCop	`74.125.197.26`	Not listed
PSBL	`74.125.197.26`	Not listed
Spamhaus ZEN	`74.125.197.27`	Not listed
SpamCop	`74.125.197.27`	Not listed
PSBL	`74.125.197.27`	Not listed
Spamhaus ZEN	`64.233.178.27`	Not listed
SpamCop	`64.233.178.27`	Not listed
PSBL	`64.233.178.27`	Not listed

The IP lists are checked against your MX hosts, which receive your mail. The servers that send it can be different and are not visible in DNS.

What each list means and how to get off it: delisting, list by list.

The rest of the report

SPFFailSPF needs 11 DNS lookups and the limit is 10, so receivers return a permanent error and SPF fails.
DKIMWarningDKIM key found at google: 1024-bit RSA key. RFC 8301 says signers should use at least 2048 bits.
DMARCWarningDMARC is at p=none, which makes no request about failing mail. Once reports show all your senders pass, move to quarantine.
MXPass1 MX host, and it resolves. Mail is hosted by Google Workspace.
BIMINot foundNo BIMI record. BIMI is optional, and it needs DMARC at quarantine or reject before any inbox shows a logo.
MTA-STSNot foundNo MTA-STS record. It is optional; it tells senders to refuse delivery without verified TLS to your listed MX hosts.

Run the full report on your own domain

Which lists are checked

Your domain

Asked of three domain lists

Spamhaus DBLDomains seen in spam, phishing, malware and botnet control
SURBLDomains in phishing, malware, spam and other abuse
URIBLDomains used by spammers, on black, red and grey lists; grey shows as a warning

Your MX hosts’ IPv4 addresses, up to 4

Asked of three IP lists

Spamhaus ZENSBL, CSS, XBL and PBL in one zone; a PBL listing shows as a warning
SpamCopAddresses reported by SpamCop users
PSBLAddresses that hit its spam traps and are not known mail servers

Your sending servers’ addresses

Not checked

DNS does not publish them. Send yourself a message, read the address in the Received line your own mail server added, and look it up on each list’s site.

Each list’s answers are read as its own documentation defines them.

Why a list can show could not check

Some lists refuse queries from public and cloud resolvers, and our server asks through one. A refusal comes back as a code that does not mean listed: 127.255.255.254 from Spamhaus, 127.0.0.1 from URIBL and from SURBL when access is blocked. The checker reads those codes, and timeouts, as could not check. With a key for Spamhaus’s Data Query Service configured, it asks Spamhaus that way instead.

How delisting works, list by list

Spamhaus: Removals go through the reputation checker; SBL listings through your network provider (SBL page). Spamhaus says removal never costs anything.
SURBL: Look the domain up and follow its removal form (SURBL FAQ).
URIBL: Look the domain up at lookup.uribl.com. Delisting needs an account.
SpamCop: Automatic. Without new reports, an address stays listed for 24 hours.
PSBL: Anyone can remove an address with its removal form, and an address expires after a few weeks without spam-trap hits.

Fix the cause first, or the address is likely to be listed again. Not being listed is one signal: Google also asks senders to keep their spam rate below 0.3%, which no lookup can see.