SpamAssassin rule
RDNS_NONE
Sending server has no reverse DNS
+1.274 points
Combination of other tests (meta rule)
What RDNS_NONE means
The IP address that delivered the message has no PTR (reverse DNS) record. Large providers treat this as a strong spam signal, and Gmail requires valid reverse DNS from all senders.
The rule's description in SpamAssassin: “Delivered to internal network by a host with no rDNS”
How to fix it
Ask your hosting provider to set a PTR record for the server's IP to a host name that resolves back to the same IP, such as mail.yourdomain.com. Or send through an email service that manages this for you.
Does your email trigger RDNS_NONE?
Send it to a free test address: we run SpamAssassin, check SPF, DKIM and DMARC and show every rule with a fix.
Open the email spam checkerRelated rules
FORGED_GMAIL_RCVDGmail address sent through non-Gmail servers
FREEMAIL_FORGED_REPLYTOFree-mail Reply-To on a different From
FREEMAIL_FROMSent from a free email address
FREEMAIL_REPLYTODifferent free-mail addresses in From and Reply-To
FROM_FMBLA_NEWDOMFrom domain registered in the last 7 days
FROM_FMBLA_NEWDOM14From domain registered in the last 14 days
FROM_FMBLA_NEWDOM28From domain registered in the last 28 days
FSL_HELO_NON_FQDN_1HELO is not a full host name
HEADER_FROM_DIFFERENT_DOMAINSFrom and envelope sender use different domains
Frequently asked questions
What does RDNS_NONE mean?
The IP address that delivered the message has no PTR (reverse DNS) record. Large providers treat this as a strong spam signal, and Gmail requires valid reverse DNS from all senders.
How do I fix RDNS_NONE?
Ask your hosting provider to set a PTR record for the server's IP to a host name that resolves back to the same IP, such as mail.yourdomain.com. Or send through an email service that manages this for you.
How many points does RDNS_NONE add?
1.274 points in the default SpamAssassin ruleset (network tests on, Bayes off). A message is treated as spam from 5.0 points. Mail servers can change scores locally.