It is, they can’t access anything it’s all encrypted and truly private to you. My only problem with the free tier is that there’s a signature at the bottom saying it was sent with proton mail, which isn’t even a big deal you just have to remember to remove it every time you send something. That and the 1 gig storage limit fills up quicker than you’d think.
Email comes in from everywhere unencrypted via SMTP. Proton may be a great company, but let's make sure everyone recognizes that email (without E2E PGP) is inherently open to anyone in the chain, including at Proton, who's snooping.
I could've sworn Proton used e2e encryption (with other proton users I suppose) and that was part of why it didn't integrate well with third party tools. But yes, even if it is, the majority of people/services that you email aren't e2e encrypted so it's very important to remember.
They do have e2e for emails. Any emails between Proton Mail users are always e2e encrypted, as are any emails others send you which they've encrypted with their own maio client. If someone sends you an email unecrypted (most email is), then Proton will encrypt it for you and put it in your inbox. They can't read it after that, but there is some trust required that they don't store/look at the unecrypted email before then.
Yup! That's their implementation of E2E I mention above, should have been more specific there.
External users with PGP, or internal users of Proton mail stay encrypted. The other 99.99% of emails come in unencrypted until they are saved to the inbox.
As far as I can tell, yes. I signed up for the free tier before paying for the service, and the worst I ever got was a banner here or there advertising their paid service. Proton encrypts all your data with your password, so they literally can't access it even if they wanted to. The only info they have on you are things like when you logged in and your IP address (and I believe they've turned that info over to law enforcement when required, like any legitimate company would have to do), but their servers are in Switzerland where there are better privacy laws.