What is Proton Mail and Is It Safe?

Proton Mail is a private, Swiss-based email service that automatically encrypts messages between its users, so Proton cannot read their contents. It is a safe and legitimate choice used by millions, though how secure your account stays also depends on a strong password and two-factor authentication.

What is Proton Mail?

Proton Mail is an email service designed to give users more privacy than a typical advertising-funded email provider. It is run by Proton AG, a company based in Geneva, Switzerland. Proton AG is overseen by the non-profit Proton Foundation. The service is funded through subscriptions rather than advertising. You can use Proton Mail to send, receive and organise email in much the same way as Gmail, Outlook or another email service. The main difference is how Proton handles your messages and personal data. Proton Mail does not show advertisements in your inbox. It does not sell your data, and it does not scan the contents of your messages to create an advertising profile. This does not mean Proton can never process any information about your account. An email service still needs to handle information such as addresses, delivery times and subject lines to operate. The difference is that Proton has designed its system so it cannot read the contents of properly encrypted stored messages. Proton Mail is based in Switzerland and operates under Swiss law. Its location is relevant because legal requests involving Proton must go through the appropriate Swiss legal process. However, being based in Switzerland does not make the service exempt from the law. The Proton Mail apps are open source. Open source means the program code is published so independent researchers can examine how the software works. The apps have also been independently audited, which means outside security specialists have inspected them for weaknesses. Proton Mail is part of a wider collection of privacy services that includes Proton VPN, Proton Pass, Proton Drive, Proton Calendar and Proton Wallet. These services can be used together, but Proton Mail remains a complete email service in its own right. Proton offers both a free plan and paid Proton Mail plans, and the free plan uses exactly the same email encryption as the paid ones.

How does Proton Mail keep your email private?

Proton Mail uses several different types of encryption. They protect messages in different situations, so it is important not to treat them as the same thing.

Messages between Proton Mail users are automatically end-to-end encrypted

An email sent from one Proton Mail user to another is automatically protected with end-to-end encryption. End-to-end encryption means the message is encrypted on the sender’s device and can only be decrypted by the intended recipient. Encryption turns readable information into scrambled data that cannot be understood without the correct key. Proton’s systems still carry the message from the sender to the recipient and store it in the recipient’s mailbox. However, Proton does not have the key needed to turn the encrypted contents back into readable text. The user does not need to switch this protection on. It happens automatically when both the sender and recipient use Proton Mail. This automatic protection applies on the free plan as well as the paid plans. Paying for Proton Mail may provide additional features, but it does not unlock a stronger version of the basic message encryption.

Stored messages use zero-access encryption

Proton Mail also protects stored messages using zero-access encryption. Zero-access encryption means Proton stores the contents of the mailbox in an encrypted form but does not hold the key required to read them. The user controls the ability to decrypt the stored content through their account credentials. This protects messages while they are stored on Proton’s servers. It means Proton cannot simply open a user’s mailbox and read the encrypted message contents. End-to-end encryption and zero-access encryption are related, but they describe different protections. End-to-end encryption protects a message from the sender to the recipient. Zero-access encryption protects email while it is stored in the mailbox.

Subject lines are not end-to-end encrypted

Proton Mail does not end-to-end encrypt email subject lines. The subject line is encrypted while stored, but Proton’s systems still need to handle it. This means it does not receive the same protection as the body of a message sent between two Proton users. A subject line can reveal useful information even when the message body is protected. For example, a subject such as “Medical appointment results” or “Employment contract” may reveal the general purpose of the message. Someone using Proton Mail for sensitive communication should therefore avoid putting private details in the subject line.

Email sent to Gmail, Outlook and other providers is not automatically end-to-end encrypted

Proton Mail can send normal email to any standard email address. The recipient does not need to use Proton. However, a normal message sent from Proton Mail to Gmail, Outlook or another outside provider is not automatically end-to-end encrypted. It is normally protected in transit using TLS. TLS, or Transport Layer Security, encrypts the connection between email servers while the message is being transferred. TLS helps prevent someone from easily reading the message while it travels across the internet. It does not prevent the receiving email provider from accessing the message after delivery. For example, a normal email sent from Proton Mail to a Gmail address can be read by the Gmail account holder. Google’s systems must also be able to process and store that message because it has arrived in a Gmail mailbox. Proton provides other ways to protect messages sent to people who do not use Proton Mail. One option is a password-protected message. The recipient receives a link and must enter the agreed password to open the encrypted message. Proton also supports PGP, which stands for Pretty Good Privacy. PGP is a system that uses encryption keys to protect messages between compatible email accounts. It can provide end-to-end encryption outside Proton, but both sides need to set it up correctly. These options can provide stronger protection, but they are not automatically applied to every message sent outside Proton Mail.

Proton can still see email metadata

Encryption protects the contents of messages, but it does not hide every piece of information connected to an email. Proton can see metadata. Metadata is information about a message rather than the main text or attachments inside it. Email metadata can include:

• The sender’s address
• The recipient’s address
• The subject line
• The time the message was sent or received
• The IP address from which a message arrived An IP address is a number used to identify an internet connection or device on a network. It can sometimes provide information about the connection’s approximate location or internet provider. Proton may have to provide the metadata it holds when it receives a valid order through the Swiss legal system. Swiss authorities can also order Proton to begin logging the IP address used by a specific account. This does not give Proton the ability to decrypt properly encrypted stored message contents. It can provide information it possesses, but it cannot provide readable content that it does not have the key to decrypt.

Is Proton Mail safe?

Yes. Proton Mail is a legitimate, well-regarded and genuinely private email service. It is one of the most trusted names among private email providers. However, the word “safe” can mean two different things. It can refer to privacy, meaning whether the provider or another party can read your messages. It can also refer to account security, meaning whether someone can gain access to your account. Proton Mail performs strongly in the first area. The second still depends partly on the user.

Proton Mail provides strong email privacy

Proton Mail is designed to reduce how much access the provider has to the contents of your mailbox. Messages between Proton users receive automatic end-to-end encryption. Stored messages receive zero-access encryption. Proton does not scan message contents to create advertising profiles, does not sell user data and does not fund the service through inbox advertising. This makes Proton Mail meaningfully different from an email service whose business depends on advertising or extensive collection of user information. The protection has clear limits. Subject lines are not end-to-end encrypted. Normal messages sent to outside providers do not receive automatic end-to-end encryption. Proton can also access and disclose the metadata it holds when legally required. Those limits do not make Proton Mail unsafe. They show what its encryption does and does not protect.

Your account security still depends on you

Encryption cannot protect a mailbox if someone signs in using the correct password. Proton Mail supports two-factor authentication. Two-factor authentication requires a second form of verification in addition to the password. This may be a temporary code generated by an authentication app. Proton also supports security keys. A security key is a physical device used to confirm that the person signing in is the legitimate account holder. These tools make it harder for an attacker to access an account after stealing or guessing the password. They are most effective when combined with a strong, unique password. A strong password is long and difficult to guess. A unique password is not used for any other website or service. Reusing a password is particularly risky. If another website suffers a data breach, an attacker may try the exposed email address and password on Proton Mail and other services. Changing email provider does not remove this responsibility. Proton can provide secure systems and account protection tools, but it cannot make a reused or easily guessed password safe.

Proton Mail is legitimate and trustworthy

Proton Mail is not a scam or a temporary email service operated by an unknown company. It is run by a Swiss company, funded by subscriptions and overseen by the non-profit Proton Foundation. Its apps are open source and independently audited. Proton also publishes transparency reports about the legal requests it receives. These features do not mean users must place no trust in Proton. Every email provider controls important parts of its own infrastructure and must operate the service correctly. They do provide ways for outsiders to examine Proton’s claims and hold the company accountable. Open-source apps can be inspected. Audits can identify weaknesses. Transparency reports show how the company responds to legal demands.

Proton Mail is private, not anonymous

Privacy and anonymity are not the same. Privacy limits who can access the contents of your messages and how your information is used. Anonymity means your activity cannot be connected to your identity. Proton Mail provides strong privacy, but it does not guarantee anonymity. An account may still be connected to identifiable information through its use, recovery details, payment method, contacts, messages or internet connection. Proton also complies with valid Swiss legal orders and may provide the metadata it holds. It can be ordered to start recording the IP address used by a specific account. It cannot provide readable copies of properly encrypted stored messages because it does not possess the decryption key. Proton Mail should therefore be understood as a private email service, not as a way to become invisible or avoid lawful investigation.

How does Proton Mail work day to day?

Proton Mail works like a normal email service for most everyday tasks. You receive a Proton Mail address and can use it to send messages to any valid email address. Other people can reply normally, even if they use Gmail, Outlook, Yahoo Mail or an email account provided by their employer. You can access the mailbox through webmail. Webmail means using an email account through a website in a browser. Proton also provides mobile apps for phones and desktop apps for computers. Messages, folders and account settings can be accessed across supported devices. The free plan can be used through the website and mobile apps. People with a paid plan can also connect Proton Mail to traditional desktop email programs through Proton Mail Bridge. Bridge is a program that allows compatible email clients, such as Outlook, Thunderbird and Apple Mail, to communicate with Proton’s encrypted system. When you send an email to another Proton Mail user, the message is automatically end-to-end encrypted. When you send a normal email to someone using another provider, it is delivered as standard email and normally protected in transit with TLS. The receiving provider can access and process the delivered message. For more sensitive messages sent outside Proton, you can use a password-protected message or PGP. These require additional steps and may require cooperation from the recipient. This means Proton Mail can be used as an ordinary email address without limiting you to conversations with other Proton users. The strongest automatic privacy applies when both people use Proton Mail. Proton Mail is a safe, private and legitimate email service. Its encryption gives it less access to message contents than many traditional providers, but it does not hide all metadata or make users anonymous. Whether it is right for you depends on your needs, and keeping the account secure still requires a strong password and two-factor authentication.