For my xF installation, I have a third-party service that checks my user table to see if a particular user exists. If they do and they are in the "Registered" group, it will give them perks on this service.
However, I don't want newly registered users being moved to the "Registered" group until after they have confirmed their email (i.e. so until then they are in the "Unregistered / Unconfirmed" group. Is this possible in vanilla XenForo? If not, is there an add-on or tweak I can do that will allow me to do this?