A method and an apparatus for scaling E-mail (electronic mail) address book databases for devices with limited storage capacity and synchronization of a first set of mail with a second set of mail at the message/folder level. A memory contains a mail subsetter for automatically generating a default personal address book and a mail synchronizer for application independent E-mail synchronization. A pseudo unique identification is generated for each message or folder in the mail boxes to be synchronized. An event log is then generated for each mail box. The memory also has a Synchronization mechanism for making the first set of data and the second set of data equivalent by using the information in the Change List generated by the Change Detection Mechanism. A processor runs the mail synchronizer.