The following should guide you to resolve the majority of issues that can prevent your users from successfully logging on to Outlook Web Access. Before you can effectively troubleshoot this issue you should know, or confirm, the following information:
1. If users are receiving an error, what is the exact wording of the error message and does it include an HTTP (IIS) status code that can help you isolate root cause?
2. If a call stack is provided when clicking Show Details, does the exception provide any clue that can help you isolate root cause?[…]