It depends on what kind of system you're setting up I guess. And which kinds of mails you're getting.
At 23 we receive photo uploads via email through qmail. Qmail acts a an SMTP server and pipes all mail to a Python script, which interprets the content of the mail. Then individual photos are added to the openacs system through XML-RPC. (We're switching from qmail to Postfix soon; the principle is the same though.)
