There are many configuration issues that can cause Exchange clients to not
be able to log on to the server. This is only one possible cause.
If the steps above do not resolve your connectivity issue, the next steps
1. Read this blog post on certificate mismatch warnings to see if it matches
2. Run the Exchange BPA on the SBS 2008 server.
3. Run the Remote Connectivity Analyzer.
This posting is provided "AS IS" with no warranties, and confers no rights.