If you do not have Microsoft Exchange Server or choose to maintain the user directory information manually, you can edit the information in the user directory. To edit user information, however, you must have SQL Server administrator permissions on the server. Be aware that if you manually enter user information and then decide to use synchronization, all information you have entered will be overwritten with the information from Exchange.
Warning If you use Microsoft Exchange Server to synchronize your user information, you cannot manually edit your user directory. The only information you can change from the Edit User command is the Exchange mailbox for a user who has multiple Exchange mailboxes. Changing a user's Exchange mailbox will cause Exchange Server to synchronize with the new mailbox for the user.
To edit user information