XWEB: "Failed To Get Inbox" Error May Occur If Name Is Ambiguous

CAUSE

The specified alias or user name may not be unique within the Microsoft Exchange Global Address List. Permutations of ambiguity include any Last Name, First Last, or Alias entered in the logon screen that is equal to any of the following for any other mailbox: For example: John Doe [alias jdoe] and Joseph Doenfron [alias doe]. If Joseph enters his alias in the logon screen, it will return one of the above errors because of the ambiguity of his alias with John's last name as the server attempts to resolve them.

This can occur if you join one or more sites that contain multiple users with the same alias or display name. If an ambiguous (non-unique) name is detected, then Microsoft Exchange Server is unable to resolve the name to a specific mailbox, and the above error messages are returned.

   Alias              jamessmith
   Last Name          Smith
   First Last         James Smith
   Last First         Smith James
   Last, First        Smith, James
   user@domain.com    jamessmith@microsoft.com