It's too bad Zen Cart uses the email address as the user name. Maybe we could change that?
Hmmmmm.!

Amazon uses the email address as the user name.
Hotmail uses the email address as the user name.
paypal uses the email address as the user name.
e-bay uses the email address as the user name.
google uses the email address as the user name.
e-greetings uses the email address as the user name.

Hmmmmm.!