feature request: mailbox domain whitelist/blacklist to restrict email addresses

I noticed that AJAX Register already has a parameter named "block these usernames" on the "filter" Tab of its options. However, this option can only restrict "usernames", not "emails". What if we want to put some restrictions on the email addresses for registration?

For example, I only want to allow specific email domains to register, like "@mycompany.com", this rurle can ensure that people outside my company can not register there. Or, maybe I want to reject certain email domains, like "@mail.xx" .

So I suggest a new feature: "whitelist/blacklist of email domains". Both blacklist and whitelist is needed.

Thank you.

Thanks. I added it to my TODO list.