In gmail and I believe some other email clients have the ability to put a button in the subject of the email that says "View Ticket"...it's a great way to highlight the email that is related to a trouble ticket.
Several other ticketing systems support this (see attached jpg) and ebay is doing it with a "Track Package" button. I believe we will start to see this more in the future.
I believe it's called Email Markup, but is based on schema.org stuff.
https://developers.google.com/gmail/markup/reference/go-to-action
Thanks,
-Owen
