What does an email blacklist check look at for cold email?
A blacklist, also called a blocklist or DNSBL, is a list of IP addresses or domains that sent spam. Mail servers look up every incoming connection against the lists they trust, and refuse or junk mail from anything listed. This checker asks five public lists about each IP, and asks a known-listed test address at the same time, so a list that refuses our question shows as "could not check" instead of a false clean result.
Why is Spamhaus not in this blacklist checker?
Spamhaus is the list that matters most, and its free access is for non-commercial use only, so a public tool cannot query it. Check your domain and IP on Spamhaus's own checker. It is free and covers both. Our guide on checking if your email is blacklisted explains how to read the result without mistaking an error code for a listing.
My domain shows no IPs. Is that a problem for cold email?
Usually not. When Google Workspace or Microsoft 365 sends your email, your domain has no sending IPs of its own: it uses theirs, and they keep them clean. For those senders, domain reputation matters more than IP lists. Check your records with the domain checker and watch your bounce and complaint rates.
What should I do if my IP is on a blacklist?
Stop sending cold email from it, find the cause first (a bad list, a compromised account, or a spam trap), then follow the list's own removal steps shown in the result. Most lists drop a listing on their own once the spam stops. Never pay a third party for removal. Our guides to spam traps and burned domains cover what to do next.