See the details here
//removing apostrophe from fields...
$personname = "{pfx_listname___name_raw}";
$personname = preg_replace("/'/", "'", $personname);
$personname = preg_replace("/?/", "'", $personname);
//assign $output variable the email body html
$output = '<p>The new subscriber '.$personname.' sent you a message, login to view it.</p>';
//send $output back to Fabrik
return $output;
$myDateElement = strtotime($row->date_time);
$date = new DateTime();
$datenow = $date->getTimestamp();
$datediff = ($datenow - $myDateElement);
$diff = round($datediff / 86400); //difference in days
return ($diff == 10); // To send email on 10th day. Change this value to send nth day.