Does it have a spot where you can set the From address? If not that could well be the problem, we have a new email system that requires the "from" email to be one actually on your account.
Also, can you verify that you have a legitimate vBulletin install? Yours is missing the license # that should be there if you got it from vBulletin's member area.
Edit: And yeah you'll need to get a license # to be unsuspended, cause vB has no record of your domain in their system.