About reverse dns lookup
Reverse DNS finds the hostname for an IP address by looking up its PTR record.
Why it matters
- Mail servers often reject messages from IPs with no reverse DNS.
- It helps identify the owner of a server in logs.
- The PTR record is set by whoever controls the IP, usually your hosting provider.
A worked example
Looking up 203.0.113.10 may return mail.example.com. For a mail server this name should also resolve forward to the same address, which is called forward-confirmed reverse DNS. Many receiving servers treat a mismatch as a sign of spam.
Setting it
- Ask your hosting or cloud provider, since they own the IP block.
- Use a name that belongs to your own domain.
- Test after the change with the lookup.
Email deliverability
Large mail providers often check reverse DNS. A mail server with an IP that has no PTR record, or one that does not match its sending name, is more likely to be placed in spam.
