Yes! Just got SMTP auth working with exim4 on my mail server. I can now send emails from anywhere I want, and they are all sent nice ans safely through my server. Major victory for me, as my friend needed this quite a bit and it frees up a box that we can use for Asterisk stuff now. And it means I don't have to run a mail server on my server in the living room as well. Bonus goodness all around.