I brought this to Ricks attention yesterday and he is going to effect this change shortly, in the interim if your site is having trouble registering users with 4 letter domains in their mail addresses you can open AddUser.php and find this section:
// ----------------------
// Check the email format
And change it to this:
<pre>
if (!eregi("^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,4})$", $Email)) {
$html -> not_right($ubbt_lang['BAD_FORMAT'],$Cat);
}
</pre>
I believe that this effects versions prior to 6.3 or so.
Regards,
Brett Harris
Infopop Corporation