Logging outgoing message content
This feels like a question that's been answered before, but Google has turned up nothing, so here I am.
I have a RHEL server running sendmail that sends out a variety of notifications to a huge user base. Today, my manager got an email from that server, with no subject or body in it. Naturally, he's concerned that some of our users might've received similar messages and he wants me to investigate.
I can see that messages are being sent out if I review /var/log/maillog, but it doesn't show me any of the message content. What I want to do is log all outbound messages' contents, including the subject and body.
I realize this can generate a LOT of data very quickly, so naturally I would set up logrotate to clear it out on a pretty frequent basis.
Also, I'm not opposed to changing my mailer daemon (to postfix, for example).