Add the 'Export to Google Calendar / iCal' links to the bottom of the ticket email for Event Tickets

add-export-links-to-email.php

<?php
/**
  * Description: Adds the 'Export to Google Calendar / iCal' links to the bottom of the ticket email
  *
  * Instructions: Copy the snippet into your theme's (preferably child theme's) functions.php file.
  * Note: Design can be adjusted with css in wp-content/plugins/event-tickets/src/views/tickets/email.php 
  * or better, create a template override for that.
  * Info on template overrides can be found in our Themer's Guide
  * https://theeventscalendar.com/knowledgebase/themers-guide/ 
  *
  * Plugins:        Event Tickets (https://wordpress.org/plugins/event-tickets/)
  * Author:         Luca Tumedei
  * Last Updated:   January 19, 2018
  */

add_action( 'tribe_tickets_ticket_email_ticket_bottom', 'add_export_buttons_to_email' );

function add_export_buttons_to_email( array $ticket ) {
    global $post;
    $post = get_post( $ticket['event_id'] );

    /** @var Tribe__Events__iCal $ical */
    $ical = tribe( 'tec.iCal' );

    $ical->single_event_links();
}