Fix the “username is not valid for UserPrincipalName” error message in Exchange 2007

After an upgrade to Exchange 2007, you may get some errors related to your account and User Principal Name (UPN). This particularly occurs when you have users where no domain name is filled in at User Logon Name at the Account tab in Active Directory.

The following error indicates that you have not set a domain name at the User Logon Name:

Object domain/organizational unit/username has been corrupted and it is in an inconsistent state. The following validation errors have occurred:

username” is not valid for UserPrincipalName. Valid values are: Strings that includes
‘@’, where ‘@’ cannot be the last character..

To solve the problem, you should fill in a domain name for every user who hasn’t got one. If you have only a few users without domain name, you could do it manually. If there are more than 10, I would suggest using ADModify. ADmodidy is a tool with a GUI, which offers you many functionality in a very easy way to modify attributes in Active Directory.

You can download ADModify from here:

Practical note: When setting attributes with ADmodify, don’t forget to test first with a small group of users!

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This was the answer to my problem, thank you