This module provides a list of email domains that could potentially be Accepted or not during registration and optionally on user profile update.

If it is applied to existing user, you can also customize a reminder to the user upon login.

It can be used in other form creating a custom validation with function:

email_domain_restriction_validate_email(array $emails)
It will return a boolean. True if it's a valid email, false if it's not.

Further features:
List of all the email fields and enable or disable the default resctriction funcitonality.
Customize the restriction functionality for each email field.
Show or not show domain list to the user.

Supporting organizations: 

Project information