I have improved the mail_from_check
content_filter (which reaches version 1.8 today!), you can now chain with other filters and besides the domain checks (if the Return-Path and From: header have the same domain but different users) the script can also check if the Return-Path domain is a subdomain of the From: header. Like it happen on some maillists:
Return-Path: < www @ server1.domain.org >
From: < forums @ domain.org >
Always you can whitelist pieces or full addresses of Return-Path (with RegEx), like ebay that has a Return-Path of:
The content_filter also does verify if the email is rfc2822 compliant (by having all the required headers).
This is beeing enjoyful! I also derived this content_filter to integrate 3 antivirus at once and fully scan the email before final delivery. You can find it over here
*Edit: Mail_From_Check.Content_Filter is now updated to 2.0, now it does many tricks including chaining to mail_scan.sh from outside Postfix!
My Best Regards,