Where does the PHP email get processed before it is sent out to the email server? It seems that some vBulletin thread notifications and privates notifications do not hit the email server and I am trying to find out if there is a way that I can track those down?
Not in there unfortunately. To make it even worse (better) - vBulletin will send emails out to users when they register and need to verify; to the admin when a new user registers; or if the user has the email activated, that works.
I started a support ticket in the vBulletin to see what they might think of is the problem, but I need to wait until someone knows how to sign into Windows.
I also checked the inetpub/mailroot - but nothing in the queue or badmail within the past few days