tofubl

Airtable or nocodb might be suitable for this. Or Nextcloud Forms. But hard to advise since it's not clear if your focus is on data entry or visualization.

I'm low key on the lookout for something like this as well, to gain independence from mail providers, and I've had a browser tab for Mail Archiver open for a few months now but never got around to trying it out. Maybe this would solve your problem?

This looks friendly. I gave up setting up Authelia after my last attempt, but I might give it another go with this when motivation hits me. Some documentation for Traefik integration would be nice.