Well, I’ve solved it! I now have a web interface (accessible via VPN, although, in principle, I could expose it to the internet) that allows fast, full-text search of all my old emails. Here is the recipe:
Installed notmuch via my distro’s repository and set it up (notmuch setup & notmuch new). This creates a new folder in your maildir directory containing full-text search info.
Installed netviel via python3 -m pip install netviel and then ran it via python3 -m netviel
That’s it! This let’s you search locally. I actually did a few more steps because I wanted to containerize this thing so I could run it on my NAS. I’d be happy to go into detail about that too, if you’re interested. One hiccup was that, for some reason, netviel binds to 127.0.0.1 instead of 0.0.0.0, and there is no way to change that without compiling the project yourself. But, I found a workaround for my Docker container where you can use socat bound to 0.0.0.0 to redirect requests to netviel, so that requests from other computers appear local to netviel.
Anyway, that makes it all sound more complicated than it is. I am super-pleased to have solved this problem at last!