Great article, and the best one I have found so far. 
However,I think that something is missing from the current tutorial (information about setting up maildir). I was getting some directory issues when i telneted on port 143. Then I realized that had to do a maildirmake on /home/vmail/[domain]/user to create the mailbox , then after that it worked just fine. My question now is : will i have to do that for every user? I thought there was a routine that would automatically create the directory after i add a user to the database.

Thanks again for this Article.