If you want to send a private message to someone and ensure that they are the only ones who read it, protecting it with a password only the recipient knows is a solid choice. Fortunately, secure email providers ProtonMail and Tutanota make this process easy and highly secure, and you can use both for free.
Why Send a Password-Protected Email?
When you send an email to a standard webmail address like Gmail, the server receives the email and notifies the recipient. The server can see the entire contents of the email, and any devices set up for use with that email address can notify the recipient of a new message.
This usually takes the form of a push notification with a visible subject line and a preview of the message contents. Even on a mobile device that’s locked, this can give away information to anyone looking over the recipient’s shoulder.
On a shared computer or tablet, the email might download automatically via clients like Apple Mail. All it takes is a click or two to read the entire contents, regardless of whether the email was intended for someone’s eyes or not. The message might be indexed by local search engines and may show up at other times.
If the message in question is sensitive, this might not be ideal. If you’re serious about having only the intended recipient see the contents of your email, protecting it with a password seems like an obvious choice. As long as you can communicate the password to the recipient privately, your message can be read without the risk of anyone else seeing it first.
In particular, the services we’ll be using today don’t transfer any of your message (except for the subject line) to the recipient’s email server. This means that the message contents won’t even show up when searched for in a webmail or desktop client.
Sending Password-Protected Email with ProtonMail
ProtonMail is one of the web’s best-known secure email providers. The service is based in Switzerland, where data protection laws are strict. It uses end-to-end encryption, so that email contents are stored in an encrypted format that not even ProtonMail’s servers can decrypt.
ProtonMail automatically encrypts all messages between users of the service, with an option to use PGP encryption for contacts who are using other email services. But there’s also an option to simply send a password-protected email to anyone, regardless of which email service they use.
To do this, you’ll need to sign up for a free ProtonMail account. You don’t need to provide your name, an existing email address, or any other identifying personal information.
Once you’ve signed up and logged in, click on the “Compose” button in the top-left corner of the screen to begin writing your message. When you’re ready to send your message, click on the Encryption “padlock” icon along the bottom of the compose window.
This is where you can set your password (which must be typed twice for confirmation) as well as an optional password hint. If you’re sending mail to someone and you haven’t communicated a password to them already, you can use the hint field to prompt them to enter a password that only they would know.
Hit the “Set” button to lock your email. You can now click on the Expiration time “hourglass” icon to determine when your email expires. All emails sent via this method will expire within 28 days by default, but you can pick a shorter time period if you like. When you’re ready, hit Send to finalize your message.
Everything except the subject line and the recipient will be encrypted and hidden. The recipient will receive a notification that they have a password-protected email and a link waiting for them. When the link is clicked, a password field will appear, which can be used to decrypt the message.
Sending Password-Protected Email with Tutanota
Tutanota is another well-known and trusted secure email provider. The company is based in Germany, a country with some of the strongest data protection laws in the world. Tutanota also uses end-to-end encryption so that data on the server is only visible to the person who owns the email account.
Like ProtonMail, Tutanota also encrypts messages between users of the same service. Tutanota also includes a password-protected email mechanism that works almost identically to ProtonMail’s, except that Tutanota’s implementation also encrypts and hides the subject line, too.
To send mail via Tutanota, sign up for a free account. Just like with ProtonMail, you don’t need to provide identifying information to sign up. Just pick a username and a password, and away you go. Once you’re signed up and logged in, click on the “New email” button to begin composing your message.
Enter an email address into the “To” field to reveal an optional password field. You can toggle the password requirement using the secure “padlock” icon in the subject field. Tutanota will remember the last password you set for the email address supplied—or you can set a new one.
With your message composed, hit Send, and Tutanota will deliver a message notifying the recipient that there is an encrypted email waiting for them. When they click the link in this email, a password field can be used to decrypt the message so that it can be read.
Like with ProtonMail, Tutanota’s password-protected messages also expire. Your message will be available at the supplied link until the next time you send a password-protected message to the same email address.
How Is This More Secure Than Webmail?
The beauty of this solution is that the contents of your messages (except for ProtonMail’s subject line) never even touch the recipient’s email servers. Nothing you say will be visible in an unencrypted format, since the message contents only ever exist on ProtonMail or Tutanota’s servers.
If your email provider is required to hand over the contents of your inbox due to a legal request, the contents of the email won’t be saved anywhere. The same thing applies if there’s a data breach and your inbox is compromised.
This means that the contents of your message cannot be scanned by Gmail’s AI, indexed by local search features on a mobile device or desktop, or appear in a push notification. The most a recipient will see before decrypting the message with a password is a notification that there’s an email waiting for them.
There are drawbacks to this method too. Many people are unwilling to click on links in email messages, and it’s even possible that some spam filters could incorrectly divert your encrypted mail to junk. Also, since the messages expire, it might be easy to lose them, especially if the recipient hasn’t realized that they’re there.
It’s also not an infallible system. Someone could guess the password, or the recipient could pass the link and password on to other people. Never assume that information is safe purely because it was password-protected at some point.
Why Not Use Gmail or Outlook?
The best native protection that Gmail has to offer in this department is the confidential email feature. This uses a one-time passcode to prove that the person opening the email has access to the mailbox it was sent to, but this method isn’t much use if the inbox has already been compromised.
Outlook also offers some protection using S/MIME encryption, which requires certificates to be set up on your device and that the recipient uses a mail application that supports the standard. It’s a far cry from simply entering a password, and it doesn’t work with the webmail version of Outlook, either.
What About Sharing the Password?
How you deliver the password could be just as important as this process. If possible, do so in person so that you know that the person you are speaking to is who they say they are. Failing this, you could use a secure messaging service like Signal to send a self-destructing message.
Learn more about securely sharing passwords using a password manager.