I followed Jeffrey Gellens article
and all seems to be working fine, apart from one thing.
I have one odd problem. Mail is showing up on the server in the user's Maildir, but when a client connects nothing shows in the Inbox. (Have tried a debian box with Iceweasel and a Windows Xp with Outlook Express).
Outoging mail is being sent fine.
Great article though, and I'm becoming an Arch Linux fan too...