A customers Windows Mobile Phone stopped syncing e-mails, etc, looking at the server we could see this error within the logs.
Event Type: Error
Event Source: Server ActiveSync
Event Category: None
Event ID: 3005
Unexpected Exchange mailbox Server error: Server: [servername.domain.local] User: [user’s e-mail address] HTTP status code: . Verify that the Exchange mailbox Server is working correctly.
After following the instructions linked to within in the error (that was after getting off the floor because the link actually worked), the problem still wasn’t resolved.
After a little Googling and not getting very far. I noticed on another server that worked you could get to http://server/exchange/owa both internally and externally but only externally on the server that wasn’t working and the error code I received was a HTTP:400, which is the same code mentioned in the description.
This is a SBS 2003 box, so I ran the firewall wizard and after that I could get to http://server/exchange/owa internally as well as internally and the Windows Mobile Phone started syncing again. Problem resolved. 🙂