How would I go about enabling SMTP authentication with VPOPMAIL to have my users authenticate with the server via SMTP instead of the POP before SMTP. I have found that this is the easiest way for my customer's instead of expaining how/why the have to check their mail before sending mail.
There are various patches for Qmail to support SMTP AUTH.
Here's one that Bill Shupp recommends in his toaster document: <http://members.elysium.pl/brush/qmail-smtpd-auth/>
(See <http://www.shupp.org/toaster/> for more info on Bill's excellent document on setting up a new qmail-based server with all the bells and whistles.)