as far as i can see the email is being sent to the is_valid_email function in includes/email.php
Did you change something there?
@Rickard: what would change if he used a non-english language pack?
The code below return 1, so the only reason for me is that he has another version of the is_valid_email function.
<?php
function is_valid_email($email)
{
return preg_match('/^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,4})$/', $email);
}
echo is_valid_email("wopio@tlen.pl");
?>
or maybe he changed this part in admin_options.php:
$form['admin_email'] = strtolower($form['admin_email']);
if (!is_valid_email($form['admin_email']))
message('The admin e-mail address you entered is invalid.');
?