SpamAssassin Rule: RCVD_IN_MAPS_RSS
Standard description: Relay in RSS, www.mail-abuse.org/rss/
The message was received via a relay listed in the DNSBL relays.mail-abuse.org.
The criteria for listing is that the relay address appears to be that of an "open relay" that will relay email from unauthenticated and untrusted users.
Since 2005, mail-abuse.org is operated by Trend Micro
The default scores for this rule can be found in the online list of tests.