SYMPTOMS

When an inbound email is being checked locally by SpamAssassin, it is triggering the rule RDNS_NONE, which is increasing the possibility of an email incorrectly being marked as spam.

CAUSE

This occurs because SpamAssassin expects to get the PTR details from the Received header in the email. MailEnable does not add this resolution to the header and the SpamAssassin process does not perform this check.

RESOLUTION

The RDNS_NONE check can be disabled in the SpamAssassin local.cf configuration file. This is done by assigning a score of zero to it, by adding the line:

score RDNS_NONE   0

If you wish to block emails from locations which do not have a PTR record, use the PTR Record Check option under the SMTP Security settings in the administration program.