Making Exchange ActiveSync Work

Troubleshooting
The Windows Mobile implementations of EAS provide error codes when things go wrong. (Sadly, the PalmOne Treo 650 reports only a few generic errors and has no device logging, making it a much more difficult device with which to troubleshoot.) A complete discussion of EAS troubleshooting would occupy an entire article in itself—for excellent information about this topic, see Jim Westmoreland's "TechNet Support WebCast: Troubleshooting Microsoft Exchange Server 2003 ActiveSync issues" (http://support.microsoft.com/?kbid=836024)—but I can give you a few highlights to help you get started.

The most important foundation for troubleshooting is to understand the error codes you're getting. Microsoft hasn't published a comprehensive list of all potential error codes, but the EAS-troubleshooting Webcast transcript has some valuable nuggets of information. Here's some information about several common errors:

• MIS_XX or SYNC_XX errors indicate a problem with the EAS server. For instance, SYNC_5 typically occurs because integrated authentication is disabled on the EAS virtual directory.
• HTTP_XXX errors indicate communication problems between the device and the server. These errors can be pretty generic: For example, HTTP_401 means you have an authentication problem, but the error message doesn't display the actual problem. If you get these errors, check the IIS logs and your EAS server application event log. When I first tried to set up EAS, I got this error and, thanks to the event log, quickly determined that bad authentication settings on my front-end server were causing it. HTTP_403 means that the target account doesn't have permission to use EAS.
• Internet_XX errors indicate communication problems with the device and the Internet. For example, INTERNET_7 means that the device can't resolve the DNS name you entered for the server, and INTERNET_45 and INTERNET_55 typically mean that the synchronization failed because the server certificate couldn't be validated.
• ConnMgr_XX errors appear when the Connection Manager software (e.g., the client side of EAS) encounters an error. These errors are fairly rare.
• Dev_XX errors are reported by the device. For example, the common DEV_1 error tells you that the device doesn't have enough free memory to complete the synchronization, and DEV_3 indicates that a timeout occurred during the synchronization.
• Error codes that begin with 0x are Windows HResult error codes. You'll see these errors only if some kind of unexpected (and hence, uncaught) error occurs.

The first way to test whether EAS is working is to see whether you can reach the \Microsoft-Server-ActiveSync directory on your Exchange server. You should always get a 501 Not implemented message when you try to access this directory by using an HTTP GET request, regardless of the device you're using or the presence of SSL. To test whether EAS is working at all, try using a desktop machine inside your firewall to load that URL. If that works, try loading the URL on your device's Web browser. If you can't resolve it with SSL, try disabling SSL. If you still can't load it, you're probably experiencing some kind of name-resolution problem. . . .