Sending IP checker
Blocklist status across 8 major lists, plus the reverse DNS checks Google and Yahoo require of anyone sending them mail.
What this checks
- Forward-confirmed reverse DNS
- Not just that a PTR record exists, but that the name it gives resolves back to the same address. A PTR on its own proves nothing — anyone can point one anywhere. Only a matching pair counts, and Google and Yahoo both require it.
- Generic reverse DNS
- Names that embed the IP address or advertise a dynamic pool are treated as a strong negative signal by receivers. It is a common reason mail from an otherwise clean address lands in spam.
- Blocklists
- Eight lists verified to be operational. Weighted honestly: a Spamhaus SBL listing is an emergency, a UCEPROTECT listing usually is not, and a Spamhaus PBL listing on a home connection is the system working as designed.
Checking your domain’s records instead? Use thedomain checker. Diagnosing one specific message? Use the header analyzer.