First of all if you have not tried Group-Office you really need to:
It's amazing. I have it configured to work with IMAP authentication. It works exactly like squirrel mail but it's a VERY easy sell to my clients.
It's easier to use than outlook and they don't have to pay for anything.
However, I am having 1 issue. I can't get it to connect to the database as a regular user. I can only connect as the root user.
I was wondering if anybody else has come across this issue.
I'm using Ubuntu 9.10 Perfect Server w/ ISPConfig 18.104.22.168
Also, are there plans for better GroupOffice integration? It's truly an amazing project.