I am not sure of the provider login.
Yes ,they need to use email address for register ,but most of the admin will register for the provider by themself.
To handle the username changes ,I have two option.
1.) just change the email address alone and dont change the username value.It means that once they created teh account ,they cant change the username.But practically it leads to confusion to the user
2.) just tweak login page to use the email address field and login field to make the user login.
It means that once customer login they cant change the username (login field ) ,but they can change the email address and during the login we need to check the username agianst login field and email address field .
I feel second option will works better without any problem if you implement it correcly.
Originally Posted by milla_c
1. If you use the e-mail address for username, does the providers also use their e-mail address as username? I guess most providers will also register as customers - then they will have to have 2 e-mail addresses?
2. How do you handle it when a user changes his e-mail address? Does the username also change and how do you then keep track of the user's orders under the previous username (e-mail)?