Problem that in the former nk2 file ( outlook 2003 ) you see an username with a number afterwards. ( This problem occured ina windows 2008 R2 envoirement with exchange 2010 )
To solve this issue you need to execute the following steps.
First start the Powershell for exchange 2010. enter the command: get-mailbox <username id> | fl LagencyExcahngeDN
1. DC = Domain name, DC=local
2. OU = MyBusiness ( location where you stored your users )
3. OU = Users
Edit the legancyExchangeDN rename the name the correct way by removing the numbers.
NOTE: when done this all other users has to remove the name of that person from the mail history. Otherwise they can’t email the person you’ve changed.