Running Exchange 2010 and in the process of migrating users from Exchange 2003. After migrating about 150 users several users are now receiving the following error with Outlook - "The action cannot be completed. The connection to Microsoft Exchange is unavailable. Outlook must be online or connected to complete this action." Users can still access email via OWA but Outlook gives the error when attempting to setup the user profile. Currently only about 3 users with the issue, all other users work continue to work and new users can be setup inside Outlook without an issue. Does not matter the version of Outlook 2003, 2007 or 2010 or the operating system, the issue follows the user to different computers. A working user can be setup on a computer and but a user with the issue will login to the same computer and receive the error and Outlook will not configure. The issue appears to follow the user account. Comparing the user accounts in AD shows all are set correctly, accounts have not been looked and no changes have been made to the account in AD.

Does stopping and restarting Outlook fix the issue? How about refreshing the user's Outlook profile by deleting the last letter from their name and then clicking Check Names?Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

Hi, Is the setting "Encrypt data between Microsoft Outlook and Microsoft Exchange" set in the Outlook Profile (Security Tab) or not? It has to be if you require encryption for RpcClientAccess (default in RTM) Get-RpcClientAccess | fl Name,EncryptionRequiredMartina Miskovic - http://www.nic2012.com/

Hi, Have you tried to recreate the mail profile in Outlook? Jonas Andersson | Microsoft Community Contributor Award 2011 | MCITP: EMA 2007/2010 | Blog: http://www.testlabs.se/blog | Follow me on twitter: jonand82

Starting and stopping Outlook does not correct the issue or refreshing the name, I have deleted the affected users profiles in Outlook and when attempting to resolve the name the error occurs. I have had the user login to another computer and attempted to setup Outlook and they receive the same error. The issue follows the user to another computer. Originally users where XP and Outlook 2003, they were migrated from Exchange 2003 to 2010 w/o issue, problem came up about 2 weeks after migration. I have tried setting up the users on Windows 7 and Outlook 2010, same issue. In Exchange I added my account to have Full Access Permissions on two of the users and I can setup the user when logged in as me in Outlook, my normal user account is NOT an Exchange Admin or Domain Admin account. When attempting to resolve the name Outlook will return with SMTP=username. In a working Outlook the user does resolve by name in the Address list and is not hidden in the address book. I have used Autodiscover and also set the profile to point to the CAS and CAS array by IP and name, same issue. Encryption is not enabled on the Exchange server and checking or unchecking "Encrypt data between MS Outlook and Exchange" setting does not make a difference. Name : RpcClientAccess EncryptionRequired : False Thank you for you help.

That SMTP=username suggests to me that the user account is corrupted in some fashion. Please use ADSI Edit to look through all the properties of the affected mailbox to see if you can find that value anywhere.Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

After checking both several working and all non-working users via ADSI Edit I do not find any attributes that appear corrupted, values in all fields for users look the same, only varying values for the users.

Hi there, I'd suggest you compare the output of Get-mailbox, and collect a netowrk monitor logs from both the client and CAS server for further analysis. It could be helpful to see what exact error occurs when Outlook is trying to connect Exchange CAS server.Fiona Liao TechNet Community Support