First, if your running W2K server with active directory,Active Directory manages users, mailboxes for Exchange 2000. Therefore you won't see mailboxes under recipients, all global addresses. You can, however preview all mailboxes users etc from any of the address lists under recipients by highlighting the list you want (like all contacts or default global address list and right clicking, then open the properties window. On the lower right corner of the window, you'll see a preview button, clickthe preview button. This will show who (or what) will be included in that address list. All users with the domain exchange email xxxx@ will be listed. You delete mailboxes via deleting the account from Active Directory, (a prompt when deleting a user will come up asking if you want to delete the mailboxes as well as the account) You can manually delete the mailbox without deleting the user account by going to Active Directory users and computers, users, highight a user name and then right click. A list of options becomes available including Exchange tasks. Click exchange tasks. This will put up a screen where you can move a mailbox, delete a mailbox or enable instant messaging. However with a plain old delete account from Active Directory including mailboxes, the effects may not be instaneous. Exchange periodically scans the Active Directory user lists and deletes mailboxes that are no longer active in Active Directory. That is an automated function of Exchange server.
Hope this answers your question