Mailbox.org yeah. And use a client you like. Skip proprietary Tuta.
What also works is using SyncThing. That way you can sync any app that uses files that you want. I use Obsidian for note taking which creates .MD files in a designated folder, I sync that folder with my phone.
For those with a robot vacuum you might want to look into Valetudo. Or just not connect it to the internet.
You didn't ask for it but I'll give you 3 recs from Belgium. The first is Yong Yello and probably made me realize that cohesive concept albums are a thing. Themes are alcoholism, cheating but not in a cool way, relationships and workaholism. He started out as a producer and you'll hear that in his melodic music.
Brihang, on the other hand, raps in West Flemish, a Belgian dialect, and has a more poetic style.
And if you want a hiphop artist to bop your head to you should probably look into Zwangere Guy. He is from Brussels and raps mostly in Dutch but combines it with French.
As a Belgian I have no clue how anyone can eat most of these, and that's including the European ones. Jacques, Callebaut or Galler are the only chocolate I actually buy. Cote Dor dark is decent though.
Or Leonidas, Neuhaus or any small chocolatier for chocolate "bonbons", the fancy filled chocolates.
I only use streaming services to discover new music. General listening to music I like, is through local files. Those are always plug and play. No need to wait. Just listen to whatever you want.
Tv shows or movies are also downloaded and streamed from Jellyfin, a local media server on my pc. Local just works. And I'm the owner of my files.
Balatro, Slay The Spire en Hades 2
Can't you just use Thunderbird as desktop app?
Mailbox.org (option if you want custom domain) or Posteo.de
Avoid infomaniak. Company is anti anonimity, CEO said only criminals want it. As a result they are supporting the anti encryption laws coming to Switzerland.
I've tried this one I got fined because it sent me through a road that was recently switched to "license holders only". Mostly my fault because I didn't see the sign but another time it tried to send me through roadworks and refused any alternatives. However great the idea of OpenStreetMaps is, community based maps are only as good if you have community members nearby.
I'll stick with Waze for navigation.