Source of version: 2
Exchange ActiveSync is extension of Exchange 2003 that allows a Pocket PC or Smartphone (2003, 2003 Second Edition or Windows Mobile 5.0 device) synchronize with Exchange. Microsoft provides Exchange ActiveSync for free with Exchange 2003.
The original implementation of Exchange ActiveSync required the client to poll the server. However with Exchange 2003 Service Pack 2 and Windows Mobile 5.0 AKU2, Exchange is now able to push e-mail directly to the device.
Prior to Exchange 2003, Microsoft released Mobile Information Server for Exchange 2000. This was the first release of synchronization software for Exchange however it was not free.
[http://www.pocketpcfaq.com/faqs/activesync/exchange_errors.php|Exchange ActiveSync Error Codes]
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