Send iCal with Mailgun PHP SDK

gistfile1.php

<?php

require 'vendor/autoload.php';
use Mailgun\Mailgun;
use Sabre\VObject;

// Instantiate the Mailgun Client
$mg = new Mailgun("MG-API-KEY");
$domain = "Your Domain";

// Create calendar invite with Sabre VOject lib
$cal = new VObject\Component\VCalendar();

// Create a meeting invite that lasts 2 hours on the same day
$vevent = $cal->add ( 'VEVENT', array(
    'summary' => $subject,
    'location' => 'Meeting room 1',
    'dtstart' => new DateTime( $mtg_date . ' 09:00:00', new \DateTimeZone( 'America/Toronto' ) ),
    'dtend' => new DateTime( $mtg_date . ' 11:00:00', new \DateTimeZone( 'America/Toronto' ) ),
    'method' => 'REQUEST'
) );

// Make iCal String
$data = $cal->serialize ();

// Dump the string to a temp file
$tempFile = sys_get_temp_dir() . "/invite.ics";
$fileHandle = fopen($tempFile, "w");
fwrite($fileHandle, $data);

// Send the message
$mg->sendMessage($domain, array('from'    => 'bob@example.com', 
                                'to'      => 'recipient@domain.com', 
                                'subject' => 'Meeting Invite', 
                                'o:campaign' => 'mailgun_campaign_id',
                                'text'    => 'Anything can go here'), 
                          array('attachment' => array($tempFile)));

// Kill the temp file
unlink($tempFile);