Be sure the display name in Active directory Users and Computers for this account says the correct name. This is on the General Tab. Also, on the exchange tabs (if you don’t have these tabs you are not using the AD Users and computers snap in that comes with exchange) make sure the display name in the advanced tab is either blank or has teh correct name.
You will also want to set the proper e-mail address as the primary on the e-mail addresses tab so people start recieving the correct/new e-mail address by default.
Also, the global address list (GAL) takes time sometimes to update.
I’m not sure if the user has tried logging out and back into the PC.
If not, give this a go and you should then be able to pick up the new name.
This can also happen when the user doesn’t log out of Outlook properly and it then hangs
onto the the old address even though replying to a message sent by the user will result in the updated name being displayed in the to field.