Quoting Meng Weng Wong (mengwong(_at_)dumbo(_dot_)pobox(_dot_)com):
[snip]
IF the connection is SMTP auth'ed,
We assume that the MUA will set "From: user(_at_)vanitydomain(_dot_)com".
We assume that the ISP will set "Sender: user(_at_)isp(_dot_)net".
Curious as to how to how many here can map an SMTP AUTH login to a
specific sender address?
My customers auth with a mailbox name that may have many addresses
delivered to that mailbox. In some cases a catchall is the only
address or a catchall in several domains. I know catchall's are
evil but customers want them and customers pay the bills.
Just thinking out loud.
John Capo
Tuffmail.com