How to Encrypt an Email in Outlook (and Mark It Confidential)
Email is a postcard, not a sealed letter — anyone handling it along the way can read it. For most messages that's fine. For a passport scan, a contract, medical details or bank information, it isn't. Outlook can encrypt a message so only the person you sent it to can open it, and can stop them forwarding or printing it.
Quick reference
| What you want | How |
|---|---|
| Encrypt one email (new Outlook) | Compose → Options → Encrypt |
| Encrypt one email (classic) | Compose → Options → Encrypt (or Permission) |
| Stop forwarding | Encrypt → Do Not Forward |
| Label as Confidential | Sensitivity button |
Do you have it?
Encryption in Outlook comes with:
• Microsoft 365 Business and Enterprise plans (most work and school accounts).
• Microsoft 365 Personal or Family when using Outlook.com or new Outlook with that account.
• Microsoft 365 Personal or Family when using Outlook.com or new Outlook with that account.
Free Outlook.com accounts and Gmail/IMAP accounts added to Outlook don't have the Encrypt button.
1. Encrypt an email
New Outlook and Outlook on the web:
1. Click New mail and write your message.
2. Click Options on the ribbon (or ⋯ → Show message options).
3. Click Encrypt, then choose:
• Encrypt — the message is encrypted; the recipient can read it, reply and forward within encryption.
• Do Not Forward — encrypted, and the recipient can't forward, copy or print it.
4. Send.
2. Click Options on the ribbon (or ⋯ → Show message options).
3. Click Encrypt, then choose:
• Encrypt — the message is encrypted; the recipient can read it, reply and forward within encryption.
• Do Not Forward — encrypted, and the recipient can't forward, copy or print it.
4. Send.
Classic Outlook:
1. In the message window, click the Options tab.
2. Click Encrypt (older versions: Permission) and choose Encrypt-Only or Do Not Forward.
3. Send.
2. Click Encrypt (older versions: Permission) and choose Encrypt-Only or Do Not Forward.
3. Send.
A banner at the top of your message confirms the encryption before you send.
2. What the recipient sees
• Outlook users in Microsoft 365 open it like any other email — the decryption is automatic.
• Gmail, Yahoo and others receive a message saying You've received a protected message with a Read the message button. They sign in with their Google/Yahoo account or request a one-time passcode sent to their email. The message opens in a secure web page.
• Gmail, Yahoo and others receive a message saying You've received a protected message with a Read the message button. They sign in with their Google/Yahoo account or request a one-time passcode sent to their email. The message opens in a secure web page.
Tell people to expect it the first time, or they may think it's a phishing attempt — which, ironically, is good instinct.
3. Sensitivity labels
Many organisations set up sensitivity labels — Public, General, Confidential, Highly Confidential. Click Sensitivity on the ribbon when composing and pick one. The label is stamped in the header, and depending on how IT set it up, it may encrypt the message, add a watermark, or restrict forwarding automatically.
If your company uses labels, use them. It's the easiest way to apply the right protection consistently.
4. What encryption does and doesn't do
Does:
• Stops anyone intercepting the email from reading it.
• With Do Not Forward, stops the recipient forwarding, printing or copying.
• Protects attachments too (Office files stay protected even after download).
• With Do Not Forward, stops the recipient forwarding, printing or copying.
• Protects attachments too (Office files stay protected even after download).
Doesn't:
• Stop the recipient photographing their screen.
• Protect the subject line — that's always readable. Keep it bland.
• Guarantee the recipient's device is secure.
• Protect the subject line — that's always readable. Keep it bland.
• Guarantee the recipient's device is secure.
5. Encrypt attachments only
If you just need to send a sensitive file, an alternative is to password-protect the document itself (Word: File → Info → Protect Document → Encrypt with Password) and send the password separately — by text, not in the same email. Or share it from OneDrive with a link that requires sign-in and expires.
Troubleshooting
There's no Encrypt button. Your account or plan doesn't include it (see above), or in new Outlook it's hidden under ⋯ → Show message options. Ask IT if you're on a work account.
The recipient can't open it. Make sure they're using the exact address you sent it to, and that they chose Sign in or One-time passcode on the Read the message page. Passcodes expire after 15 minutes.
I need to revoke an email I've sent. For Do Not Forward messages, open it in Sent Items → ⋯ → Remove encryption / Revoke (availability depends on your plan). Otherwise, there's no recall for encrypted messages.
Wrapping up
For anything you wouldn't put on a postcard, click Options → Encrypt before you send. Use Do Not Forward for things that must stay between you, and keep the subject line vague.
