Exchange ActiveSync is a protocol which allows mobile devices to synchronize data with Exchange mailboxes. Synchronizing is a process of reconciling data between a device and the appropriate Exchange mailbox.The protocol synchronizes your mail, calendar, contacts, and tasks over the air with Microsoft Exchange Server.xchange ActiveSync is an additional server-based synchronization agent that removes the dependency on a desktop computer, using the wireless capability of the device. The two methods of ActiveSync can be used in combination or independently.