[drschwabe]

Another option, hypothetical, is you export your emails to a common format like markdown (with embedded meta directly in each file; 1 per email or in a pair where the secondary file is the same name but stores meta only ie- in json) and then open them in any note-taking app or wiki or static site generator that works on markdown files (with some extent of configuration presumably, extra points if the app makes it sensible to easily organize your emails for optimal viewing). You could serve the files over HTTP, probably less hassle than running a secondary IMAP server, or alternatively you could sync them to your device(s) over ssh via git or zfs or an app like Syncthing.

[pmontra]

Thunderbird to HTTP looks simple enough to be a side project sometimes in the future. It could integrate with a backup server I'm planning to setup. Thanks.