couldn't you just just hack the sig submission box with an if/else statement
i.e. with a
PHP Code:
if (strlen $_POST['signature'] = '%abc.com%') {
echo ("$_POST['signature']") } else {
echo ("signature suspended") } //end conditional
or (this is the one i've placed my faith in
PHP Code:
if ("isset($_POST['signature'] = '%abc.com%')") {
echo ("$_POST['signature']") } else {
echo ("signature suspended") }; //end conditional
not sure if either will work but i was trying to show you my idea/hunch.