ActiveSync provides a great synchronization experience with Windows®-based PCs and Microsoft Outlook right out of the box.

ActiveSync acts as the gateway between your Windows-based PC and Windows Mobile-based device, enabling the transfer of Outlook information, Office documents, pictures, music, videos and applications to and from your device.

In addition to synchronizing with a desktop PC, ActiveSync can synchronize directly with Microsoft Exchange Server 2003 so that you can keep your e-mail, calendar data, tasks and contact information updated wirelessly when you’re away from your PC.

Changes in ActiveSync 4.2 help resolve connectivity related issues with Microsoft Outlook, proxies, partnerships, and connectivity.
- Microsoft Outlook Improvements: Resolves issues relating to error code 85010014.
- Proxy/DTPT interaction Improvements: Improved auto configuration of device Connection Manager settings when desktop has no proxy path to the internet.
- Improved Desktop Pass Thru behavior with ISA proxy failures.
- Partnership improvements: Better resolution of multiple devices with the same name syncing with the same desktop.
- Connectivity Improvements: Better handling of VPN clients (resolve unbinding of protocols from our RNDIS adapter). New auto detection of connectivity failure with user diagnostic alerts.

Notes:
- Faster file transfer speed and photo sync via Outlook are only available for Windows Mobile 5.0-based devices. For customers using Windows Mobile 2003 or 2002-based devices, please continue using ActiveSync 3.8.
- Remote PC Sync (via Wifi or LAN) has been removed due to Enterprise customer feedback around security issues. If you are using this feature on a Windows Mobile 2003-based device, please continue using ActiveSync 3.x or earlier.
- Beginning in 2006, customers using Microsoft Exchange 2003 Service Pack 2 with devices running the Messaging and Security Feature Pack for Windows Mobile 5.0 will benefit from the following feature enhancements in ActiveSync 4.1: Direct Push Technology, local device wipe, and certificate-based authentication to Exchange Server.