DirectAdmin sucks for setting up mail and having it actually work. I have never had any problems in the past with mail from the site with CPanel, but ever since the went to DirectAdmin (against my advice, by the way) it has been a freakin' nightmare.
I do have one suggestion that will help things as far as getting around the site and doing things easier... put some of the non-vb files in the forums directory in their own directories. You have way too much extra stuff in there.