I'd like to be able to use Windows Messenger 5.1 on my corporate LAN and only allow Exchange accounts to login. I want to permanently disable the .NET Passport Account from being able to login. I know I can go to options and uncheck the checkbox, but I want something that will stop the user from being able to change it themselves. I'd prefer a registry change or something along those lines. I already blocked port 1863 at the firewall level, but it just uses one of a multitude of servers running on port 80. Anyone have any ideas? Thanks!