• Proton is not an Email app but mainly an email provider that locks you into its own app.

• Proton does not provide e2e encrypted email outside its own environment (so any mail within proton will be encrypted but not outside - and it’s far harder to do the later due to point one)

• Proton is heavily run by US citizens living in the US - and therefore to some extend fall under the homeland security act and similar laws, including pressure by the current administration.

• Proton claims to be based on Swiss privacy laws. One should be aware that Swiss data protection laws are amongst the weakest in Europe, that service providers can (and mostly are) forced to monitor cross border traffic and that Swiss intelligence services have a long history of unlawful overreach and extremely close cooperation with US services. To what extend Proton is affected by this is unclear, unlike other Swiss based service providers they refuse to comment on this(and they would be allowed to comment, don’t get me wrong)

Just to be aware. I know there are a lot of fans of proton on Lemmy,but there are far better services available nowadays. If the Swiss privacy law does not bother you Infomaniak is an option, alternativly mailbox.org is an option within the GDPR sphere. (Can be bad or good depending on your own situation)

Neither of them is an app, nevertheless,but they work with any major app,e.g. thunderbird.