I figured that probably wasn't the best way... I checked the mlm.php file. Here's the code... it seems to be fine. Not exactly the same as yours should still work, right? Does it have anything to do with changing the opt-in info to false?
// Send a confirmation message to the subscriber
function SendSubscriptionMessage() {
global $msg_confirmation, $admin_address, $path_to_script, $cmd, $list, $listfordisplay;
global $admin_name_full, $admin_webAddress, $script_name, $script_version;
global $firstname, $lastname, $company, $email, $admin_notifications;
$url = $path_to_script . "?cmd=unsubscribe&list=" . urlencode( $list ) . "&email=" . $email;
$listfordisplay = formatlistnames( $list );
$subject = "Your subscription confirmation";
$message = $msg_confirmation;
$message = str_replace( "
- ", $listfordisplay, $message );
$message = str_replace( "", $email, $message );
$message = str_replace( "[UNSUBSCRIBE_URL]", $url, $message );
$message = str_replace( "[SIGNATURE]", "$admin_name_full\n$admin_webAddress\n$script_name $script_version", $message );
$headers = "From: $admin_address";
SendMessage( $email, $subject, $message, $headers, $encoding );
if ( $admin_notifications == 1 ) {
$subject = "$email has subscribed to $listfordisplay";
$message = $subject . ".";
$headers = "From: $admin_address";
SendMessage( $admin_address, $subject, $message, $headers, $encoding );
}