Hi, I have tried to activate a user on Unified messaging but I got an error: Summary: 1 item(s). 0 succeeded, 1 failed. Elapsed time: 00:00:00 UserDiaplayName Failed Error: An error occurred while accessing the mailbox for user username. For more information, see the event logs on server ServerName Exchange Management Shell command attempted: 'OU/UserName' | Enable-UMMailbox -PinExpired $false -UMMailboxPolicy 'UM Policy' -Extensions 'Extension number' -IgnoreDefaultScope Elapsed Time: 00:00:00 And when I checked in the Logs have: Event Type: Warning Event Source: MSExchange Unified Messaging Event Category: UMWorkerProcess Event ID: 1174 Date: 7/26/2010 Time: 2:55:14 PM User: N/A Computer: UM01-WYN Description: An error occurred while performing the following operation: 'Validate or Generate PIN' for user 'username'. 'Microsoft.Exchange.Data.Storage.ObjectNotFoundException: The Active Directory user was not found. ---> Microsoft.Exchange.Data.Directory.Recipient.NonUniqueRecipientException: Multiple objects with legacy DN /o=exchange/ou=domain/cn=recipients/cn=johhuryn were found. at Microsoft.Exchange.Data.Directory.Recipient.ADRecipientSession.FindByLegacyExchangeDN(String legacyExchangeDN) at Microsoft.Exchange.Data.Storage.ExchangePrincipal.FromLegacyDN(String legacyDN) --- End of inner exception stack trace --- at Microsoft.Exchange.Data.Storage.ExchangePrincipal.FromLegacyDN(String legacyDN) at Microsoft.Exchange.UM.UMCommon.UmUser.InitializeExchangePrincipal() at Microsoft.Exchange.UM.UMCommon.UmUser.InitializeMailboxSession() at Microsoft.Exchange.UM.UMCommon.UmUser.get_ItemStore() at Microsoft.Exchange.UM.UMCommon.XsoPasswordImpl.get_UserConfig() at Microsoft.Exchange.UM.UMCommon.XsoPasswordImpl.get_Dictionary() at Microsoft.Exchange.UM.UMCommon.XsoPasswordImpl.get_OldPa' Any Idea what that could be many thanks in advanced

It appears to be an ambiguous name resolution. What do you get if you do this: get-mailbox -resultsize unlimited |? {$_.legacyexchangedn -eq " /o=exchange/ou=domain/cn=recipients/cn=johhuryn"}[string](0..33|%{[char][int](46+("686552495351636652556262185355647068516270555358646562655775 0645570").substring(($_*2),2))})-replace " "

Thank you for your answer mjolinor, I have searched using Powershell for the Legacy and had the user that is having the issue, and when I open his attributes using: get-mailbox -identity "username" | select legacyexchangedn or get-mailbox -identity "username" | select * none of the the $_.legacyexchangedn are equal to /o=exchange/ou=domain/cn=recipients/cn=johhuryn but when I used the Exchange 2007 GUI consol I had another user having : /o=exchange/ou=domain/cn=recipients/cn=johhuryn as X500 attributes in the email tab!!!! to fix the issue I have removed the X500 attributes from the second user and enabled UM for the 1st user. do you have any idea why this happened? Thank you so much

I'm afraid I can't help much there.[string](0..33|%{[char][int](46+("686552495351636652556262185355647068516270555358646562655775 0645570").substring(($_*2),2))})-replace " "

Does that “Another user” being migrated from another mail system? Usually, X500 address is added in order to reply old messages that contain such address. If the address isn’t migrated along with the mailbox, it could be added manuallyJames Luo TechNet Subscriber Support (http://technet.microsoft.com/en-us/subscriptions/ms788697.aspx) If you have any feedback on our support, please contact tngfb@microsoft.com

Thank you all for your answers