I am attempting to find a desirable solution so I can send email through my colo server from anywhere. In the past, I was using the POP-before-SMTP method, which opens up relaying for a small timewindow if you check your mail first. I would kind of like to do actual authentication in order to make it just that much more secure. However, I do virtual hosting and store passwords in a MySQL database, of course. Postfix does not play nicely when it comes to SMTP authentication and MySQL. It looks like this may be my only solution, but I’ll have to scrounge around a bit more.