this is the joomla 1.0.10 code (taken from joomla.php, about line 2737)
[code:1]if ((trim($this->email == ""«»)) || (preg_match("/[\w\.\-]+@\w+[\w\.\-]*?\.\w{1,4}/", $this->email )==false)) {[/code:1]
Now this is what joomla uses to see if emails are valid emails or not .
If you change this code as fallow you will have:
[code:1]if ((trim($this->email == ""«»)) || (preg_match("/[\w\.\-]+@hotmail.com/", $this->email )==false)) {[/code:1]
now only emails with domain hotmail.com are allowed (or seen as true correct email address)
that’s it….if u try register with an email different from the @hotmail.com it will ask you to input a valid email address.
Now in your case, it wont let other email addresses the opportunity to register.
I would like to know if there is a way to have more than 2 domain names able to register