Sadly the best product mail-wise is currently MS Exchange online. Privacy wise Posteo is probably the best.

Always has been a sketchy company - any company who claims Swiss privacy laws are good (and in reality operates out of the US) is lying to you.

Proton is and always was sketchy.

A company claiming “Swiss privacy laws” as their base while de facto operating out of the US is highly problematic. Switzerland has the weakest privacy laws of all European countries, has laws in place for extensive intelligence agency placement within their tech companies and has a history of intelligence agency overreach. The USA can easily make companies and executives do what they want due to the whole Homeland security act clusterfuck.

I wouldn’t touch then with a ten foot pole if data privacy was ones goal.