Welcome to the forums monk707
Don't have any experience with oscomerce but usually an internal server error indicates that the file does not have the appropriate permissions or was uploaded in binary mode when it should have been done in ascii mode.
The mail will bounce back to the sender as not being able to be delivered.
Test it, send a message to sales@yourTCHdomain.com from a valid email address and wait for the bounce.
I took a look at it with IE and it displays just fine if the font is set to smallest, smaller and medium. If you bump it to larger it starts to get screwy. Take it to largest and it overlaps pretty badly.
In cPanel select Default Address. Make sure the :fail: is entered for your domain.
That should automatically reject any mail coming to your domain for which you do not have an address set up.
In cPanel go into the Web Protect function. Select the folder that is already protected. On the screen that appears remove the check mark in the box labeled:
Welcome to the forums panther.
I am not aware of any email issues using cPanel here and I've been here over 2 years.
As Serpentine stated each server has it's own mail server and there are several data centers.
Total Choice has no control over how the page is rendered. It is a part of cPanel. They would be the ones that you ask if it could be changed.
www.cpanel.net
The only other suggestion I can think to offer is make sure you have installed all the security patches for your vBulletin board.
I am a member on a vBulletin board too and they have been hacked several times in the past year.