SpamAssassin Rule: DNS_FROM_RFC_DSN
Standard description: Envelope sender in dsn.rfc-ignorant.org
Explanation
The domain of the envelope sender is listed in the DNSBL dsn.rfc-ignorant.org.
The criteria for listing is that the servers listed in the domain's MX records must accept messages with the empty sender address (MAIL FROM:<>) so that Delivery Status Notification (DSN) messages can be delivered.
Further Info
The default scores for this rule can be found in the online list of tests.