The “Virus Bounce Ruleset” is a SpamAssassin ruleset to catch “backscatter”.
Backscatter is mail you didn’t ask to receive, generated by legitimate, non-spam-sending systems in response to spam.
Read More »Catching unsolicited bounces (backscatter) with SpamAssassin
If you want to hide email source, you can easily remove Received field in mail header using header_checks.
Read More »Removing Received field in mail header with Postfix