1. In a system having a server that is operable to communicate with a mobile device over a wireless network, the server including a server application database for storing copies of data items that are transmitted to the mobile device and the mobile device including a memory subsystem for storing data items on the mobile device, a memory management method comprising: determining that additional memory space is needed on the mobile device; if additional memory space is needed, then communicating with the server over the wireless network to determine if a copy of one or more data items are stored in the server application database, and if copies of the one or more data items are stored in the server application database, then deleting the one or more data items from the memory subsystem in the mobile device to create additional memory space, whereby the mobile device verifies that copies of one or more data items are stored in the server application database before the one or more data items are deleted from the memory subsystem to create additional memory space on the mobile device; wherein a list of one or more data items identified in the server application database is received from the server application database in order to determine if copies of the one or more data items are stored in the server application database, and wherein data items included in the list are deleted before data items that are not included in the list.