One thing I keep seeing in discussions about “secure” or “encrypted” email is a misunderstanding of what services like Proton Mail actually protect.
To be clear, I’m a fan of Proton and other zero-knowledge email providers. They offer a significant privacy advantage over traditional providers like Gmail and Outlook.
The key benefit is that your mailbox is encrypted in a way that the provider does not have the keys to read your stored email. In other words, Proton cannot simply access the contents of your inbox. With traditional providers, your email is encrypted on their systems, but they control the keys and can access the data when required for service operations, legal requests, compliance, and other purposes.
That’s a meaningful difference and a major reason many people choose privacy-focused providers.
However, this is where a lot of people get confused.
Having a Proton account does not automatically mean every email you send is end-to-end encrypted.
If you send an email to another Proton user, the message is encrypted end-to-end by default. Neither Proton nor anyone in between can read the contents.
But when you send an email to a Gmail, Outlook, Yahoo, or other external address, the email is generally delivered like any other email. It is typically protected in transit using standard TLS encryption, but once it reaches the recipient's provider, it is no longer end-to-end encrypted by default. The recipient’s email provider may be able to access the message content.
If you want true end-to-end encryption with someone outside the Proton ecosystem, you must intentionally use an encryption method such as Proton’s password-protected encrypted messages or another compatible encryption solution. In other words, you have to choose to encrypt the message before sending it.
So the takeaway is simple:
- Zero-knowledge email providers protect your account and stored data from the provider itself.
- End-to-end encryption protects the contents of a message between sender and recipient.
- Those are related but different concepts.
- Sending from Proton to Gmail is not automatically end-to-end encrypted.
- If you need end-to-end encryption with an external recipient, you must explicitly enable it.
Privacy-focused email services are absolutely worth using. Just understand what problem they solve—and what they don’t.