We have invested heavily in owning and controlling our own server hardware at several locations within Switzerland so your data never goes to the cloud. Our primary datacenter is located under 1000 meters of granite rock in a heavily guarded bunker which can survive a nuclear attack. This provides an extra layer of protection by ensuring your encrypted emails are not easily accessible to any third parties. On a system level, our servers utilize fully encrypted hard disks with multiple password layers so data security is preserved even if our hardware is seized.
ProtonMail's zero access architecture means that your data is encrypted in a way that makes it inaccessible to us. Data is encrypted on the client side using an encryption key that we do not have access to. This means we don't have the technical ability to decrypt your messages, and as a result, we are unable to hand your data over to third parties. With ProtonMail, privacy isn't just a promise, it is mathematically ensured. For this reason, we are also unable to do data recovery. If you forget your password, we cannot recover your data.