Just recently some users started to report that when trying to access OWA authentication would fail with the following error: ----------------------------------------------------------------------------------- Reason: Unknown user name or bad password User Name: username Domain: domain Logon Type: 8 Logon Process: Advapi Authentication Package: Negotiate Workstation Name: EXCHANGE Caller User Name: EXCHANGE$ Caller Domain: Domain Caller Logon ID: (0x0,0x3E7) Caller Process ID: 6592 Transited Services: - Source Network Address: x.x.x.x Source Port: 52533 ----------------------------------------------------------------------------------- Similarly, these same users are using the RPC-over-HTTP feature and cannot log into Outlook; for me this points to IIS. To confirm an IIS issue, I disabled RPC-over-HTTP on the client and they have no issue connecting to the Exchange store. We have made no changes to IIS or Exchange for that matter. The interesting thing is, some users have no problem with OWA or RPC-over-HTTP. All AD Exchange attributes are the same - i.e. OWA Access, Mobile settings, Sync, etc... I'm inclined to think this has something to do with Kerberose or something of the likes. Thoughts?

Hi What is your exchange version? Maybe it is caused by Insufficient User Rights, you could refer to Users Cannot Log On to Outlook Web Access Because of Insufficient User Rights http://technet.microsoft.com/en-us/library/bb885050(EXCHG.80).aspx Also you could try the solutions on the thread http://social.technet.microsoft.com/Forums/en-US/exchangesvrdeploy/thread/28610378-8c02-4722-a2ce-2696f6fad147 Hope it helps Cheers Zi Feng Zi Feng TechNet Community Support

Thanks Zi. The issue has been resolved. We actually had an issue with a number of things resulting from a failing hard drive. Although there was some redundancy there were some issues - all of which have been solved. We are in the stages of migrating to O365 E3 - good bye Exchange, Lync and Sharepoint! (thank the lord). I have been dealing with issues for the past 5 years with these servers - glad to see it and them go. Thanks for your assistance.