Suggestion for "Play by email"

[hartmark]

hosting long-turns games (where people can login and make 1 turn per day or so),

When you're ready for this part you could just use https://www.playyourdamnturn.com/
You can ask on their Discord for adding the support for this game.

[FluxIX]

Interesting service; it'd be a good option.

I would like to see more support than just that for "Play by Email"; a machine-readable serialization of the actions taken which can be sent as an attachment would be great, although even better would be integration if sending the email (which would require some configuration of the SMTP server and credentials).