[daveslash]

Wait... What!? Okay, I'm admittedly ignorant of the technical details of email, but I thought "an email" was just some text (with encoding specified), some internet headers, and maybe a binary blob representing an attachment. Basically, what you see if you "view original" in Gmail. Is there additional meta data that makes up an email? Like, outside of the content "container" part of the email (similar to how image meta data is saved in the EXIF part of a JPEG file, but isn't part of the image itself)? Sorry if I phrased that dumbly.

I assume this, specifically, is what you're referring to https://schema.org/EmailMessage

[smileybarry]

They referred to such schemas like "FlightReservation"[1] for flights, "EventReservation"[2] commonly used for movie tickets, or "LodgingReservation" used for hotel bookings. The specific supporting website encodes your reservation in these formats inside the confirmation email, and Gmail picks up on that. (IIRC it used to scrape emails for that data, but most of it if not all is done via schemas nowadays)

[1] https://schema.org/FlightReservation

[2] https://schema.org/EventReservation

[3] https://schema.org/LodgingReservation