Limit registrations to one domain?

[tribedude]

I am about to launch a new board for a client and they need to limit new registrations to only 1 domain (ie their own domain). The purpose is to limit the board registrations to their own staff - making it an internal staff board.

Is there a mod / plugin available to do this? Or is there a slight change you can make to the vb code to make this happen?

Thanks,