Abstract: A method of migrating a mail post office from a first mail server H to a second mail server H2 in a mail network is disclosed. The first mail server H acts as a first mail directory synchronization server (DS Server) and the post office initially acts as a mail directory synchronization requestor (DS Requestor) to the first DS Server. The method comprises the steps of: establishing the second mail server as a second DS Server; establishing a third mail server H3 to act as a DS Requestor to said first DS Server; redirecting mail on said post office to said second mail server; removing the DS requester for said post office from said first server; deleting all user entries for said post office from a mail directory on said first server; and adding said post office as a DS Requester to said second server.