Many people have been asking how to block forged MAIL FROM:<> email addresses.
Correct me if I wrong but it seems to me that Postfix:
reject_unauthenticated_sender_login_mismatch could resolve this issue for all local addresses. If so I could see integrating this into ISPC3.
You can read up on it
here.
It is my understanding that if used with
smtpd_recipient_restrictions it will require you to be authenticated for any addresses located in
$smtpd_sender_login_maps & that can be easily specified.
Here is another post with a similar dilemma.
http://howtoforge.com/forums/showthread.php?t=47918