Well, my server runs for 19 years now without a major secuirty breach... so do I know.
But to answer OP: you cannot ever delete gmail message. Even spam is kept forever to comply with LE, since some of your real messages could by accodent go to junk. With Proton once I delete a message, its gone forever since it was part of my internal encrypted blob of messages. once I logged off deleted message is gone.
> Do you really believe Gmail and your personal server possess the same value as targets?
That's also the point. :) Why put your data into a service that has higher chance of being targetted (and you may never know if it was). Also if you're in control of the device, you'll be the one receiving the subpoena/search warrant (or a swat team), so you'll know if it was targetted.
Except they didn't "own" Google's data centers at all. They tapped a fiber optic cable outside any data centers. Every other wavelength and individual strand in that cable would have also been susceptible. Fiber optic cables aren't some secret, they're quite visible(orange) and accessible in public rightaways. So yeah Protonmail is not much safer from that level of hostility is it?
Lastly for all Protonmail's righteous talk about governments. They're own /24 is announced by an Israeli company that does defense contracting[1] and has their own hardware division - the RAD Bynet Group who makes lots of network hardware including hardware that does deep packet and SSL inspection[2]. Proton mails seems to like to brush this off but for a company that wants to position itself as a player in the fight against government intrusion into privacy, it has a pretty bad smell.
Because I acknowledged that they've responded to it with:
"Proton mails seems to like to brush this off ..."
And I don't find they're explanation particularly cogent. And for a company that makes such a big deal about their Swiss affiliation this seems to big a particularly glaring detail.
From your link:
>"Recently, malicious rumors have surfaced that our partnership with Radware means Israel has compromised ProtonMail email privacy (since Radware’s international headquarters is in Israel). These rumors have mostly been spread by conspiracy theorists who don’t at all understand ProtonMail’s technology."
Do you think that Protonamil is privy to what goes on in the hardware of either Binat-Rad Group Ltd's Radware DPI asics or the network topology in Binat-Rad Group's data centers?
And Binat-Rad does have a relationship with the Israeli government:
"In our opinion, the Company’s working capital is sufficient for the Company’s present requirements. Since our inception, we have financed our operations through a combination of issuing debt and/or equity securities, including two public offerings, research and development and/or marketing grants from the Government of Israel and cash generated by operations."[1]
And if you think that Binat-Rad is not involved in politics, see:
But to answer OP: you cannot ever delete gmail message. Even spam is kept forever to comply with LE, since some of your real messages could by accodent go to junk. With Proton once I delete a message, its gone forever since it was part of my internal encrypted blob of messages. once I logged off deleted message is gone.