deoren:
> The question I had would have been better phrased as, "Is there a way to
> limit which clients can claim to be from your domain(s) when sending mail?"
>
> After doing some additional digging it looks like "Envelope sender
> address authorization" is what I'm looking for?
>
> http://www.postfix.org/SASL_README.html#server_sasl_authz_envelope
Indeed. Besides the strict form reject_sender_login_mismatch, there
are the weaker forms reject_authenticated_sender_login_mismatch and
reject_known_sender_login_mismatch.
Note that all these look at the address in the MAIL FROM command
(the envelope sender address). Due to the design of SMTP mail, the
envelope sender (and recipient) address can differ from the From:
header address (and recipient address).
For example, you receive this message with From: my email address
but with MAIL FROM address of the postfix-users mailing list, and
with To: the mailing list address but it is delivered to your mailbox.
Wietse
