Mass email problem
 

After contacting my web host about this here is their reply:

You have faced with common mail problem of vbulletin 3.x.x. Your current version of vbulletin uses vbmail() function to send the email, instead of php mail(). You will need change all the vbmail() functions to mail(). There are three files need to be modified
1. register.php ( new member get auto mail notification)
2. sendmessage.php (send specific page to friends)
3. funtion_newpost.php (in includes folder; get auto notification when new post in the forum).

Does this make sense and how do I do this?