Here's something we learned the hard way around here.
Some users keep a dummy mailbox around for whatever reason.
To retain personal anonymity, sanity, and cleanliness. Well, sometimes we want to log into the dummy mailbox directly, not as a proxy user. And sometimes we just want to actually be in the mailbox. It just feels right. If you work on just one machine, like us, you probably have your own GroupWise mailbox open all the time.