Abstract: According to one embodiment, the invention provides a method for operating an electronic mail server system having mailboxes associated with message client devices. The method comprises receiving input to change a mailbox, said input comprising a request to change an organizational structure of the mailbox; making changes to the mailbox in response to said input; and sending a message to a message client device associated with the mailbox, the message comprising information to allow the message client device to synchronize a cached version of the mailbox stored locally in the message client device with the mailbox.