Ok, I'm fairly new to hosting. I've been doing it for ~6 months now. Currently I'm not even trying to do it to live off of... just doing it small time to help pay for my dedicated server. I'm considering trying to make a go at doing it for real, though, and have been wondering about something.

If I have a separate mail server from the web/shell server that user's accounts are on, what is the best way to keep the passwords synched up? Just tell user's to remember to change them both when they want to change? If cpanel or webmin or something is installed on both can they be linked together and both change at the same time that way? Or is it better to have separate mx hosts but after the receive the mail, run it through spamassassin and a virus scanner, just have them forward it to the web server box that the user's accounts are on?