Forum Similar feature to enter license number
 

Hello All

I'm just starting out with my first vBulletin forum. I would like a feature similar to the one used on the vBulletin forum that requires a user to enter their license number.

My requirements are slightly different and I have no idea how to go about it. I have a website that is only accessible to registered users. I would like the forum to also only be available to those that have registered. Is it possible to check the email address they use to sign up on VB against my wordpress database users, if a match is found, they can register otherwise they are assigned to a usergroup with no privileges or declined?

Sounds like a lot I know, any tips on how to get started?

Thank you