I run a Postfix mail server using Spamassassin as after-queue filter.
It works quite well, but sometimes I get spam from the network that has correct
MAIL FROM: address, but also contains, in
DATA: section, different forged address
something <at> mydomain.com.
Most e-mail client programs, including Thunderbird and Outlook, displays it using the second ( forged ) address.
I would like to block such messages automatically, but I can't do it using
smtpd_recipient_restrictions ( forged address resides in
DATA: section ).
It also have nothing to do with SPF since
MAIL FROM: ( envelope sender ) address may be correct according to SPF.
Then how can I do it using Postfix settings or Spamassassin rules ?