Thanks for putting this together.
* You want emacs - https://notmuchmail.org/notmuch-emacs/
* You don't want emacs - https://github.com/pazz/alot (I use this one, it's very nice)
Also Mutt - https://notmuchmail.org/notmuch-mutt/
What I really want is: mutt's UI, but with a SQLite3/PostgreSQL backend, and mutt not to iterate a mailbox when opening it, and an async IMAP client that reconnects as needed.
> The downloaded archive is in the mbox format
So really, these instructions are for indexing any mbox-formatted mailbox.
It may not be what you expected, but this is wrong.
The instructions tell you how to download your Gmail emails to mbox format, so they are instructions on how to index your Gmail emails.
The title makes it sound like it's instructions to setup up an alternative API to Gmail search. I was thinking something like Algolia.
More like first get yourself a host with at least 16gigs of RAM first.
With that said, I suspect given tuning based on your search patterns and usage - you could get more accurate search results when you control the indices, stop words, etc.