I don't want them to keep getting redirected though. I want them to be redirected once and then once they read the message they are good to go. Also if a member is part of two different usergroups (not userclasses, sorry

) and each group has an important message to check what would happen then? My guess is that only one important message will be displayed.
Also, with the method that you mentioned I don't think that I would be able to know who read the thread.