So, Slashdot linked to an interesting Zed rant today, which linked to this
project:
It's actually not a bad idea, and I'd been nursing a similar idea for awhile,
but as Zed says, "you’re still all afwaid of big bad monsta SMTP." My current
plan was to build something around Postfix -- all the hooks I need are there --
but if someone has a decent Ruby SMTP server, so much the better.