Maintaining a sliding view of server based data on a handheld personal computer

A computer program storage medium readable by a computing system and encoding a computer program of instructions for executing a computer process in an email system at a client computer, said computer process retrieving server email messages from an email server computer, said computer process comprising:

• getting a server list of message identification elements related to server email messages;
• determining whether any of the server email messages are on the client computer;
• retrieving header information for each server email message not on the client computer;
• analyzing the header information and determining whether the server email messages, that are not on client computer, satisfy the predetermined criteria;
• downloading server email messages to the client computer that satisfy the predetermined criteria;
• and
• starting the computer process by first executing any outstanding synchronization commands between the client computer and the server computer.

Apparatus for maintaining a selective view of server based data on a client in a network of server and client computing systems, said apparatus in the client comprising:

• a compose module composing a local item list of local email identifiers identifying those email messages on the client;
• a get module requesting a server list of server email identifiers identifying email messages on the server;
• a compare module comparing server email identifiers to local email identifiers to determine whether a server email message on the server is not on the client;
• header request module responsive to the compare module and getting header information from the server for each server email message not on the client;
• test module detecting from the header information whether each server email message not on the client satisfies a predetermined criteria;
• a retrieve module responsive to the test module and downloading to the client server email messages that satisfy the predetermined criteria;
• a preservation module preserving on the client only local email messages that satisfy the predetermined criteria or server email messages downloaded by the retrieve module;
• wherein the preservation module comprises:
• a marking module marking a “keep” flag on local email messages that satisfy the predetermine criteria and local copies of server email messages downloaded by the retrieve module;
• a delete module deleting all email messages on the client not marked with a “keep” flag.