Automatically-effected move of a subscriber between electronic message service systems in a network

In a network (10) of voice-mail message service systems (12-14), each system includes an arrangement (22) for automatically moving the serving of one or more subscribers from itself to another system. In response to administrator (29) input, the source system retrieves each moving subscriber's mailbox (200) contents, translates subscriber I.D.s appearing therein into universal names and extension numbers, and transfers the translated contents, including delivery lists (222) and messages (211), to the destination system. The destination system creates a new mailbox for each moved subscriber, translates the universal information into subscriber I.D.s, and populates the new mailbox with the transferred contents. The source system informs third systems of the move, so they can update their information. During audits, the source and destination systems search their databases to find any information affected by the move and update it; the source system also deletes the moved subscribers' old mailboxes.