Perhaps take a look at my quick guide to vpopmail with mysql at http://www.pipeline.com.au/staff/mbowe/isp/vpopmail-mysql.htm
Also available is a more comprehensive mail server guide at http://www.pipeline.com.au/staff/mbowe/isp/webmail-server.htm
I've probably said it before but it deserves saying again: Mr. Bowe deserves 'wicked-mad-props' for the guides listed above. I've referred to them many times, and I'm running Solaris! Having all the steps written out in excruciating detail, along with having noted all those hundreds of little 'gotchas' that go along with complex installations, makes these guides a 'Must have' for just about anyone using this suite of software.
summary of the above: BRAVO!
The Nicest Misanthrope on the Net