How to Send a Secure Email

What Is Encrypted Email

The original email protocol was not conceived with security in mind. Because the communication between email servers was plain text, anyone could easily capture entire email messages and read their content. Over the years, several encryption mechanisms for email messages were designed, some more secure than others. Email encryption is often paired with email authentication to verify that an email comes from who it claims to be from.

Today, many people are asking, “What does encrypted email mean?” because online privacy has become a hugely important topic that concerns most people on this planet. Fortunately, sending encrypted email messages could hardly be easier, and we explore various ways how to send encrypted email messages in the next chapter of this article.

S/MIME vs. PGP/MIME

But before we explain how to send a secure email from any device, we should first talk about the two main email encryption methods and briefly go over the differences between: S/MIME and PGP/MIME. If you’re not interested in what goes under the hood when you send encrypted emails, you can skip this subchapter without missing anything essential.

S/MIME stands for Secure/Multipurpose Internet Mail Extensions, and it’s widely accepted email encryption method that’s based on asymmetric cryptography. This method is supported by iOS devices as well as several major service providers, including Gmail and Outlook. S/MIME is often described as a centralized method for sending encrypted email because a centralized authority must choose the encryption algorithm and key size for it to work.

PGP/MIME stands for Pretty Good Privacy/ Multipurpose Internet Mail Extensions, and the main thing that separates it from S/MIME is its decentralized model, which empowers users to choose exactly how they want to encrypt their messages using third-party encryption tools, making flexible and versatile.

How to Send Encrypted Email

Standard messages are not safe, but the good news is that there are many great secure email providers that let you easily send encrypted messages to anyone. One such service is ProtonMail, which was founded by a group of CERN scientists in 2014.

ProtonMail is a free, open source email services that uses client-side encryption to protect messages and user data before they are sent to ProtonMail servers. There are also other ways how to send secure encrypted email messages, and we explore some of them in this article.

How to Send a Secure Email in Gmail

By default, all email messages sent using Gmail are protected by something called TLS, or Transport Layer Security. TLS is a cryptographic protocol designed to provide communications security over a computer network, and it’s widely used on the internet to secure everything from email to web browsing to voice and video calls.

TLS protects messages from being captured en route from point A to point B, but it doesn’t protect them against Google or anyone else with access to Google’s servers. You can, however, take Gmail’s encryption to the next level with FlowCrypt. This elegant web browser extension integrates seamlessly with Gmail, adding end-to-end encryption that prevents anyone in the middle from reading private communications.

While you’re at it, you should also consider pairing your Gmail account with Clean Email, a powerful bulk email organizer with useful automation features that can keep your inbox organized and spam-free, which is essential if you want to be truly secured.

While Clean Email can't help you with sending or encrypting emails, it can help you to get rid of tonnes of unwanted messages, including newsletters, mailing lists, and other unsolicited messages. Using privacy-conscientious algorithms that analyze only email headers containing subject line, sender and recipient information, dates, and similar metadata, the app organizes all of your messages into easy-to-review bundles, allowing you to apply various actions to entire groups of emails instead of selecting them one by one.

Email is continuously playing catch-up to keep users safe from cybersecurity threats. Privacy Guard from Clean Email provides a safety-net for your email address by cross-checking it against known security threats.

Upon identifying your email address in a security breach, Privacy Guard immediately suggests you change your password so you can minimize any potential damage. You can get started with Clean Email for free on your iOS, macOS, Android device, or in web.

How to Send a Secure Email in Outlook

Office 365 Home or Office 365 Personal subscribers can send encrypted email messages in Outlook.com. This is how to send a secure attachment and message in Outlook:

1. Go to Outlook.com.
2. Select New message at the top of the page.
3. Enter the name or email address of the person who will receive the message on the To line.
4. Enter a brief description of what your message is about on the Add a subject line.
5. Select attach to attach a file to your message.
6. Type your message.
7. Choose one of the two options available under the Encrypt button: Encrypt or Encrypt and Prevent Forwarding (follow our guide on how to automatically forward emails in Outlook.)

• Encrypt: Your message stays encrypted and doesn’t leave Office 365. Recipients with Outlook.com and Office 365 accounts can download attachments without encryption from Outlook.com, the Outlook mobile app, or the Mail app in Windows 10 or Windows 11.
• Encrypt and Prevent Forwarding: Your message stays encrypted within Office 365 and can’t be copied or forwarded. Microsoft Office attachments such as Word, Excel or PowerPoint files remain encrypted even after they’re downloaded.

1. Finally, select Send.

How to Send a Secure Email in Yahoo

Just like Gmail and all other major email services, Yahoo relies on the TLS cryptographic protocol to encrypt messages in transit, preventing intruders on public WiFi networks from capturing your online communication and reading it in plain text form.

If that's not enough for you because you want to send secure email messages that even Yahoo employees can't read, we have bad news for: sending end-to-end encrypted email messages in Yahoo is not possible without a third-party plugin.

One such plugin is Mailvelope, and we recommend it because of its open-source development process, large user base, and close cooperation with many leading email providers. Mailvelope works in Chrome, Edge and Firefox, and it uses PGP to ensure that no unauthorized person can read your email messages—not even Yahoo employees.

Here's how to send a secure email in Yahoo using Mailvelope:

1. Download the Mailvelope extension for your web browser of choice.
2. Click the Mailvelope icon and begin the initial configuration.
3. Open a new message in Yahoo Mail as usual.
4. Click the Mailvelope icon again.
5. Write your message and click Encrypt.
6. Send the encrypted email message.

To learn even more about Mailvelope and how it works, we recommend you visit the official help page.

How to Send a Secure Email on Mac

Mac users have it great because they can send encrypted messages directly from the Mail app, the email client included by Apple with macOS (including macOS 12 Monterey). To do that, you need a certificate obtained from a certificate authority. If you don’t have one, you can request it in Keychain Access right on your Mac.

1. Open the Keychain Access app and choose Keychain Access → Certificate Assistant → Request a Certificate From a Certificate Authority.
2. Enter the required information and click Continue.
3. Review the certificate, then click Done.

To import your certificate into Keychain Access, simply double-click it. Next, import the recipient’s certificate and then verify that both certificates are listed in the My Certificates category in Keychain Access.

With your and the recipient’s certificates successfully imported, you can open the Mail app and use it to send a secure email using the following instructions:

1. Choose File → New Message in the Mail app.
2. Hover your mouse over the From field and choose the account for which you have a personal certificate in your keychain.
3. Enter the recipient and select the padlock icon next to the subject field.
4. Compose your message.
5. Hit Send.

How to Send a Secure Email on Windows

Windows users can send encrypted email messages using Outlook for Microsoft 365, Outlook 2019, Outlook 2016, Outlook 2013, Outlook 2010, and Outlook 2007. Here’s how to send a secure email in Outlook 2019:

1. Launch Outlook 2019 and go to File → Options → Trust Center → Trust Center Settings.
2. There, select the Email Security and choose Settings under Encrypted email.
3. Click Choose and select the S/MIME certificate under Certificates and Algorithms.
4. Confirm by clicking the OK button.
5. Compose your message and click Send.

To learn how to send a secure email in older versions of Outlook, visit this page.

End-to-End Encrypted Email Services

We’ve already recommended ProtonMail as an excellent email service that automatically secures all emails with bullet-proof end-to-end encryption, which makes it impossible for anyone to decrypt and read year emails—even ProtonMail itself.

Apart from ProtonMail, there’s also Tutanota, a German open source, end-to-end encrypted email service with over 2 million users.

Tutanota is supported solely by donations and premium subscriptions, and it uses a hybrid method consisting of a symmetrical and an asymmetrical algorithm for extra security.

Also worth mentioning is MsgSafe.io, which is a privacy-focused email service based in one of the most secure jurisdictions in the world. MsgSafe.io allows its users to create as many email addresses as they need, and it protects each virtual mailbox with 4096-bit GPG and S/MIME encryption keys and certificates.

Conclusion

Email security is an important topic, and all email users should learn how to send a secure email to protect their privacy. In this article, we’ve introduced several ways how to send encrypted messages, and it’s now up to you to try them out and make it impossible for unauthorized third parties to read your personal correspondence.

End-to-end encrypted email services make sending secure email messages especially easy, so there’s no reason to risk having your personal information pwned by a cybercriminal.

Also don't forget to get more information on related topics as how to avoid phishing attacks and stop email spoofing by following our recommendations.