Method and apparatus for maintaining a unified view of multiple mailboxes

A unified view of mailboxes is presented. The unified view allows the user to see in one mailbox all actions performed in all mailboxes on a message. One of the clients of a mailbox has both a high cost and a low cost communication channel. When a message is received by a client from its respective mailbox without an identifier, an identifier is generated and a copy of the message is sent to the other mailboxes along with the identifier. When the user performs actions on a message on a client, the identifier for the message and the action is conveyed to the other clients in a message to the other mailboxes. The unified view can be selectably updated either over the high cost communication channel or the low cost communication channel. The presence of two communication channels enables management of the cost of performing the unification. The user can select options to control the unification process and the use of the high cost communication channel.