The simplest way to encrypt an email depends on which email service you use
Gmail, Outlook, and Apple Mail all have built-in encryption, but the steps are different for each one. Gmail's approach is the most straightforward — you toggle a single button before sending. Outlook requires you to set permissions on the message. Apple Mail uses a feature called S/MIME that you enable once in settings, then use on individual emails. None of these methods require you to install extra software or exchange keys with the person receiving the email beforehand.
The person on the receiving end does not need to do anything special to read an encrypted email from you. They open it the same way they open any other message. The encryption happens between your device and theirs, and the email service itself cannot read the contents.
Key Takeaways
- Gmail's confidential mode encrypts the message and lets you set an expiration date so the email disappears after a certain number of days.
- Outlook's Encrypt button restricts who can forward, copy, or print the message, and you can revoke access even after sending.
- Apple Mail's S/MIME encryption requires a one-time setup in settings but then works on any email you choose to encrypt.
- The recipient does not need special software or passwords to read an encrypted email — it decrypts automatically on their device.
Encrypting email in Gmail
Open the email you are composing and look for the lock icon with a pencil through it, located near the bottom of the compose window next to the trash icon. Click it. A panel will open asking you to set an expiration date and whether to require a passcode. The expiration date is how many days the recipient can access the message before it disappears — you can choose 1 day, 3 days, 1 week, or 4 weeks. If you add a passcode, the recipient will receive a separate text message or email with the code they need to enter to read the message.
If you do not see the lock icon, your Gmail account may not have confidential mode turned on yet. Go to Gmail settings (the gear icon in the top right), click "See all settings," then go to the "Advanced" tab and scroll down to "Confidential mode." Click "Enable" and save your changes. The lock icon will now appear in your compose window.
After you set the expiration date and passcode options, click "Save" and then send the email as usual. The recipient will see a message saying the email is confidential and will expire on a specific date.
Encrypting email in Outlook
Open the email you are composing. In the toolbar at the top, look for a button labeled "Encrypt" — it usually appears near the "Send" button. Click it. A menu will appear with options: "Encrypt Only" and "Do Not Forward." Choose "Encrypt Only" if you want the recipient to be able to read and reply to the message but not forward it to others. Choose "Do Not Forward" if you want to prevent them from forwarding, copying, or printing the message at all.
If you do not see the Encrypt button, your organization may not have encryption turned on, or you may be using Outlook.com (the free version) rather than Outlook through a workplace account. Outlook.com does not have the Encrypt button. If you are using a work account and the button is missing, contact your IT department.
After you select your encryption option, send the email normally. The recipient will receive the message and can open it in their browser or in Outlook. If you change your mind after sending, you can go back to the sent email, click "Revoke," and the recipient will no longer be able to access it — even if they already opened it.
Encrypting email in Apple Mail
Before you can encrypt an email in Apple Mail, you need to set up S/MIME encryption one time. Open Apple Mail, go to Mail > Settings (or Preferences on older versions), and click the "Accounts" tab. Select your email account from the list on the left. Click the "Advanced" tab, and check the box next to "Enable S/MIME." You may see a message asking you to get a certificate — if so, you will need to contact your email provider or IT department to obtain one. Once S/MIME is enabled, close the settings window.
Now when you compose an email, you will see a lock icon in the toolbar at the top of the compose window. Click it to encrypt the message. The lock icon will turn solid, showing that encryption is active. Send the email as usual. The recipient will see a lock icon next to your name in their inbox, indicating the message is encrypted.
If you do not see the lock icon in the compose window after enabling S/MIME, make sure you have a valid certificate installed. Without a certificate, S/MIME encryption will not work. Your email provider can tell you whether your account has a certificate and how to install one if it does not.
What happens when the recipient opens an encrypted email
The recipient does not need to enter a password or read software to read your encrypted email — unless you added a passcode in Gmail, in which case they will receive the passcode separately. In Gmail, they will see a message saying the email is confidential and will show them the expiration date. In Outlook, they will see the email in their inbox and can open it normally, but they will not be able to forward it if you selected "Do Not Forward." In Apple Mail, they will see a lock icon next to your name.
The encryption happens automatically on their device. Their email service cannot read the contents of the message, and neither can anyone else who might intercept it in transit. If the recipient tries to forward an encrypted Outlook email that has "Do Not Forward" enabled, they will get an error message saying they do not have permission.
When encryption might not work as expected
If you are sending to someone outside your organization in Outlook, encryption may not work unless your IT department has set up external encryption. Ask your IT team whether you can encrypt messages to people outside your company. Some organizations only allow encryption between internal accounts.
In Apple Mail, if the recipient does not have S/MIME set up on their device, they may see the encrypted message as an attachment rather than readable text. This is rare with modern email clients, but it can happen with older devices or email apps. If the recipient reports they cannot read your encrypted email, ask them to update their email app or try opening the message in a web browser instead.
Gmail's confidential mode works with any email address, including Gmail and non-Gmail accounts. The only limitation is that the recipient cannot forward the message, and it will disappear after the expiration date you set.
Encrypting attachments and large files
When you encrypt an email, any attachments in that email are encrypted too. You do not need to encrypt files separately. However, if you are sending a very large file, consider compressing it first or using a file-sharing service like Google Drive or OneDrive, which have their own sharing permissions. You can then send a link to the file in an encrypted email instead of attaching the file itself.
If you are using Gmail's confidential mode and the recipient tries to read an attachment after the expiration date, they will not be able to access it. The same applies to Outlook's "Do Not Forward" option — the recipient cannot save or read attachments from a message with that restriction.
Frequently Asked Questions
Can I encrypt an email after I send it?
In Outlook, yes — you can revoke access to an encrypted email even after the recipient has opened it. Go to your sent folder, click the email, and select "Revoke." In Gmail and Apple Mail, you cannot unsend or revoke an encrypted email once it is sent. Plan ahead and make sure the encryption settings are correct before you click send.
What if the recipient says they cannot read my encrypted email?
Ask them which email service they use and which device they are opening the email on. In Gmail, make sure they received the passcode if you set one. In Outlook, confirm they are opening the email in Outlook or a web browser, not a third-party app. In Apple Mail, ask them to update their email app. If they are using a very old email client, they may need to open the message in a web browser instead.
Does encryption slow down sending or receiving?
No. Encryption happens when ready on your device before the email leaves. The recipient receives it at the same speed as an unencrypted email. There is no noticeable delay.
Can I encrypt emails to a group of people at once?
Yes. When you add multiple recipients to an encrypted email, all of them receive the same encrypted message. In Outlook, if you use "Do Not Forward," none of them can forward it to others. In Gmail, all recipients see the same expiration date. In Apple Mail, all recipients need to have S/MIME set up to read the message.
Is encryption the same as marking an email confidential?
No. Marking an email as confidential is just a flag or label — it does not actually encrypt the message. Anyone with access to your email account or the recipient's account can still read it. Real encryption scrambles the message so that only the intended recipient can read it. Use the encryption methods described here, not the "confidential" or "sensitivity" labels.