I need to create a Joomla Registration form with some extra functionality and would like some input on the best way to do this. The site is a customer portal with multiple custom user groups. When a new user is registering we need to identify the correct user group based on the email address. eg. If a users email address contains "abc.com" (such as firstname.lastname@example.org) they should be registered as usergroup A, if the email contains "xyz.com", user group B etc. Can this be achieved with the user plugin?