Accounting for references between a client and server that use disparate e-mail storage formats

In one exemplary implementation, a client receives a record from a server. The record has a server identification key that uniquely identifies the record from any other records. If the record is viewable by a user in one or more folders, there are corresponding one or more associated references that indicate which one of the one or more folders the record is viewable. For each of the one or more associated references, one or more new records identical to the received record are created. One or more client identification keys are assigned to the one or more new client records; wherein each of the one or more client identification keys uniquely identifies the one or more new client records. Each of the one or more new client records are synchronized to the record received from the server by mapping the one or more client identification keys to the server identification key.