Still need help...
Oooops! What a newbie error!
I did as you suggested but I still get the following message:
The serial number you entered is incorrect. (with the red "X" instead of the green check mark)
I used Cmd+V and the serial number copied exactly as shown in the download center.
Is it possible to issue a new version of Universal Email with a new password through my Download Center? Do you have any other ideas?