Blacklist checker
Checks a domain, its mail server and website IPs, or one IPv4 against public email blocklists, and links to the delisting page for every listing.
Not listed
Clean23 lists checkedken.so, mail server 142.250.102.27, website 104.21.10.205 are on none of the 23 lists we checked. Recheck after any spike in bounces or complaints.
3 passedNothing to do here. Open it to see the evidence for each one.ken.so clean142.250.102.27 clean104.21.10.205 cleanShowHide
ken.so
Domain lists check the name itself, as it appears in links and the From address.Mail server: 142.250.102.27
The IPv4 of smtp.google.com.Website: 104.21.10.205
The IPv4 of ken.so.Check these by hand
Big lists this tool doesn't query. Each link opens the list's own checker.Next
What the blacklist checker does
Enter a domain or an IPv4 address and the checker queries public DNS blocklists for it. For a domain it also checks the IPv4 of its first MX host and of its website. IP blocklists track servers that sent spam. Domain blocklists track domains that appear in spam, in the From address or in links. Each list comes back as listed, clean or no answer, and every listing links to the list's removal page.
The queries run on Ken's own resolver. Several major lists refuse queries that come through large public resolvers such as 8.8.8.8, which is why some free checkers show errors or false listings for them. Lists whose terms rule out a free commercial tool, or that only answer registered resolvers, aren't queried from here: the result links to each one's own checker instead.
How to read the result
A listing on one small list with every other list clean is common and often harmless. Some lists are aggressive, and some list whole ranges or networks for what a neighbor did. A listing on a widely used list is different, because receivers that use it reject or junk your mail directly.
Check what kind of listing it is. An IP listing matters for servers you control. If you send through Google Workspace or Microsoft 365, the sending IPs belong to them, and your domain is what carries your reputation. A domain listing affects every message with that domain in the From address or in a link, whichever server sends it.
No answer means the list timed out or refused the query. It isn't a listing.
How to get delisted
- Find and stop the cause first: a compromised inbox, a bought list full of old addresses, a sudden jump in volume, or a link domain shared with spammers.
- Use the list's own removal form, linked from each result. Most removals are free.
- Some lists expire entries on their own. SpamCop drops a listing 24 hours after the last report.
- Be wary of lists that charge for fast removal. Paying doesn't fix the cause, so check whether the receivers you care about use that list before you pay.
Why it matters for cold email
Cold email lists contain old and wrong addresses, and some of them are spam traps run by blocklist operators. Hitting traps gets a domain or IP listed fast. Verify lists before sending and remove addresses that bounce.
Check your sending domains, your tracking domain and every domain you link to. A link to a listed domain can sink a message from a clean sender. Check weekly while campaigns run, and right away when reply rates drop for no clear reason.