Just noticed this thread:
Not sure what exactly people have or have not done, but here is our settings that work for us.
1) PHP
Make sure OpenSSL is uncommented. (In other words, it's loading in PHP)
2) vBulletin Mail Settings (AdminCP → vBulletin Options → Email Options)
SMTP: Yes
SMTP Host: smtp.gmail.com
SMTP Port: 587 (Can be 465 or 587, one should work)
SMTP Username:
youraccount@googledomain.com (Gmail or Google Apps account)
SMTP Password : youraccountpassword
SMTP Secure Connection: TLS
(This information from Google was used to set this up when we first started:
http://mail.google.com/support/bin/a...n&answer=13287)
This setup has worked for us for a long-time without any hassles. We do have our mail hosted through the Google Apps system.