When synchronizing your mobile device with Exchange 2003 you may see the following error:

There is a good KB that covers this issue; KB886346 - "You receive an HTTP_500 error message when you synchronize your mobile device with Microsoft Exchange Server 2003".   This article deals primarily with SMTP address mismatch.   But I have noticed especially with SBS there are a couple of other factors that come into play that can trigger this error.

• URLScan ISAPI filter - if you are using URLScan it places an ISAPI filter in the ISAPI filters tab in the properties of Web folder in IIS. - Remove it.
• Location: Open IIS - expand the server icon - select properties of the Web Site folder - ISAPI filters tab.

• Permissions are incorrect on the exchange-oma website
• Location: Open IIS - expand the server icon - Expand the Web Sites folder - select the properties of the exchange-oma website - Select the Directory Security tab - select the edit button under Authentication and access control 
• The correct permissions should be:
• Integrated windows authentication - checked.
• Basic authentication - checked.
• All other check boxes should NOT be selected.

• Permissions are incorrect on the microsoft-server-activesync website 
• Location: Open IIS - expand the server icon - Expand the Web Sites folder - select the properties of the microsoft-server-activesync website - Select the Directory Security tab - select the edit button under Authentication and access control 
• The correct permissions should be:
• Basic authentication - checked.
• All other check boxes should NOT be selected.

>edwalt