I've got postfix forwarding my server's local mail using my ISP's (earthlink) smtp server and sasl authorization on a Debian Etch box.

I was forced to use sender_canonical because postfix was logging earthlink's smtp server rejecting it because it didn't come from their domain. I thought I had learned everything there was to know about forwarding email. Huzzah.

But wait! MAILER-DAEMON@hostname is forwarding me its error emails with the localhost name as the "from" and earthlink doesn't reject it. What gives? Is postfix sending it on its own? If so, how?

A second issue is how the address appears in my mail client. It shows the Sender as From: Cron Daemon <myname@earthlink.net> Can postfix rewrite the "Cron Daemon" part too?