I wrote a primitive script to copy emails from Thunderbird's storage
into notmuch, allowing one to use notmuch's power without having to
abandon Thunderbird. Perhaps you are interested in including it in the
import scripts on the notmuch website.
https://github.com/JohannesBuchner/flight-reservation-emails This works with the help of mb2md, but finds the relevant mboxes
automatically. Maybe in the future it would be interesting to treat tags
"X-Mozilla-Keys: $label1" as notmuch tags.
I started that github project today to find emails that look like flight
etickets, and make a summary of the flights with their details. Google's
Android phones have a similar feature (flight ticket wallet), but there
is nothing for laptops as far as I can tell. I implemented one
convention, but it does not cover all flight etickets at the moment.
Hotel bookings may also be interesting. Feel free to fork and expand.