Last Updated on October 11, 2026 by pg@petergamma.org
I found text of the legal advice I had received via e-mail from the Beobachter legal advice team lawyers posted on electronic billboards at the main train station in Zurich. Can Proton Mail solve this e-mail security problem?
Standard email is generally not safe for sending sensitive or confidential data. While major providers like Gmail use Transport Layer Security (TLS) to encrypt messages during transit between servers, this protection is incomplete because the data is often decrypted and stored in plain text on intermediate and final servers, where it remains accessible to providers and potential hackers.
Proton Mail is widely considered a safe and secure email service, primarily due to its end-to-end encryption, zero-access architecture, and headquarters in Switzerland, which subjects it to strict privacy laws.
The service uses open-source code that is independently audited, ensuring that Proton staff cannot read your emails or hand them over to third parties, even in response to legal requests, because they do not hold the decryption keys.
However, security has limitations: end-to-end encryption only applies when both sender and recipient use Proton Mail, while emails sent to non-Proton addresses rely on standard Transport Layer Security (TLS) during transit.
Additionally, while message content is encrypted, email subjects and contact names are not, and the company may log IP addresses temporarily for security or permanently if terms of service are violated.
But emails sent from Proton Mail to non-Proton email providers are not end-to-end encrypted by default, meaning the recipient’s provider (e.g., Gmail, Yahoo) can access and read the message content.
• Secure Alternative: To ensure the message remains encrypted and inaccessible to the recipient’s provider, you must use the Password-protected Emails feature, which encrypts the content so only the recipient can decrypt it using a password.
• Storage on Proton Side: Proton Mail still stores an encrypted copy of the sent message in your Sent folder, ensuring Proton itself cannot access your sent data.