Good evening Gordon,
Thank you for your interest in wanting to customize the email message sent to your liking.
You can absolutely modify the email message by using our themer’s guide step-by-step approach.
The file you are looking for is located in /wp-content/plugins/event-tickets/src/views/tickets and is named email.php.
As the guide suggests, you should copy that file in your own WordPress theme [your_theme_folder]/tribe-events/tickets/
Once that’s done you can tailor it to your specific needs.
Additionally, you can even completely disable the ticket email altogether if you want by using the following free plugin.
Let me know if that answers your question.
Have a great night!
Geoff B.