A script based on the GitHub library that enables the Subscription Tracking app.

smtpapilib.php

<?php 
include 'sendgrid-php-master/SendGrid_loader.php';

$sendgrid = new SendGrid('*******', '*******');
$mail = new SendGrid\Mail();
$mail->
 addTo('sebi.mihalache@gmail.com')->
 setFrom('sebastian.mihalache@sendgrid.com')->
 setSubject('Kvitto din kförs betalning nördlichen blabla Hemisphäre ciment')->
 setText('Testing %name% subject.')->
 addUniqueArgument("uid:", "sebGmail")-> 
 //addSubstitution("%name%", array("John"))->
 setHtml('<p>Testing <i>%name%</i> subject.</p>')->
 addFilterSetting("subscriptiontrack", "enable", 1)-> 
 addFilterSetting("subscriptiontrack", "text/plain", "If you would like to unsubscribe and stop receiving these emails click here: <% %>.")-> 
 addFilterSetting("subscriptiontrack", "text/html", "If you would like to unsubscribe and stop receiving these emails <% click here %>");
$sendgrid->smtp->send($mail);
echo 'Great Success!';
?>