Symptom:
When a user with:
i) username containing non-ASCII characters (above U+00FE) using NTLM Authentication or 
ii) domain name containing non-ASCII characters (above U+00FE) using kerberos authentication,

tries to login to Exchange using MAPI AO or tries to send mail, it will fail and connection is handed over to generic AO.

iii) displayname containing non-ASCII characters (above U+00FE) using NTLM Authentication will fail in keyretrieval and identity will be blacklisted.

Conditions:
When the username, displayname /domainname contains unicode characters above U+00FE.