What gets checked
The check runs on two levels, because blacklists operate on two levels:
- Domain blacklists (6 lists) — judge the domain name itself, regardless of which server sends. They mostly catch domains that appeared as links in spam: URIBL, Spamhaus DBL, SURBL, URIBL Black, ScrolloutF1, NordSpam DBL.
- IP blacklists (25 DNSBLs) — judge the IP address. The IPs of the domain's MX hosts are tested: Spamhaus ZEN, SpamCop, Barracuda, SORBS, UCEProtect, PSBL, Mailspike, abuse.ch, Blocklist.de, SpamRATS and more.
Why the MX IPs — and what that tells you
Without a real message the sending IP is unknown. So the tool checks the servers that DNS does reveal: the MX hosts. In most smaller setups those are the same machines that also deliver outbound mail — in which case the result is directly meaningful.
If you separate receiving from sending — Google Workspace inbound, a newsletter tool outbound — you only see the receiving side here. The sending IPs live in your SPF record; the full email analysis covers those.
Listed — now what?
Not every entry carries the same weight. Spamhaus ZEN and Spamhaus DBL are consulted by a great many providers and genuinely block; smaller lists such as UCEProtect levels 2 and 3 list entire netblocks along the way and are barely used by serious receivers. A hit there usually means nothing.
Delisting always comes after the cause: an open relay, a compromised mailbox, a form without rate limiting, missing reverse DNS. Delist without closing the source and you are back on the list within days — and repeat entries make the next delisting harder.
What this check cannot see
Blacklists are only one part of deliverability. Whether a message arrives depends just as much on SPF, DKIM, DMARC, your reputation with the individual provider, and the content. And a clean result here is a snapshot — lists update continuously.
For the complete picture including the actual sending IP, send an email to hello@analyzemy.email.