Hello All,
In order to set SMTP Authentication one can complete the task from Forums administrative section and perform below mentioned steps:

1) Login into vBulletin forums administrative section.
2) Go to vBulletin Options -> Email options.
3) Enter below mentioned details:
  • SMTP Email
  • SMTP Host
  • SMTP Port
  • SMTP username
  • SMTP Password
  • SMTP Secure Connection
4) Click on save changes.

Note: This setting does not work when PHP SAFE MODE is enabled.

That’s it!

Thanks,

Shane G.
AccuWebHosting.Com