GroupWise 8.0HP2 on Windows 2008 servers

I have some users who report that addresses for internal people are being stored in a weird format. I've emailed the same people and their normal (internal) name/address is what gets stored in my Frequent Contacts.

What causes this address format to be stored in a user's Frequent Contacts address book: "", even though that recipient is an internal person?

Their regular Internet email address ( may also be stored in the same Frequent Contacts book. Each is identified with the same person and, depending on which way their address book is sorted, determines which one is at the top of the list when they are offered to choose the address to use.