I'm desperately trying to get Postfix to 'rewrite' the MAIL FROM envelope so that it's always in the form of: authenticated-user@$mydomain
I've been playing with the smtpd_sender_login_maps
and smtpd_sender_restrictions
options but these don't seem to provide anyway of forcing a certain value, merely accepting or rejecting the given value.
How can achieve this?
Thanks.