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By , IT support technician

Quick Answer

Compose a new email, click the Options tab, and click the Encrypt button before pressing Send.

How to Encrypt an Email in Outlook ​

Applies to: Microsoft Outlook (Desktop & Web), Microsoft 365
Article Type: How-To
Last Updated: 2026-07-10

Summary ​

Standard email is not secure. It is like sending a postcard through the mail—anyone who touches it along the way can theoretically read it. If you need to send sensitive information (like tax forms, HR data, or Social Security Numbers) to an external client or vendor, you must encrypt the email. This wraps the message and its attachments in a digital lockbox that only the recipient can open.

Prerequisites ​

  • You must be using your company-provided Outlook account.
  • Your company must have Microsoft 365 encryption enabled.

Instructions ​

Option 1: The "Encrypt" Button (The Easiest Way) ​

This is the standard method for most Microsoft 365 users.

  1. Open Outlook and click New Email.
  2. Type your message and attach your files as normal.
  3. Click the Options tab at the top of the window.
  4. Click the Encrypt button (it has an icon of a lock).
  5. Select Encrypt-Only. (This allows the recipient to read the email and download attachments, but the email is securely encrypted in transit).
  6. Alternatively, select Do Not Forward. (This encrypts the email AND prevents the recipient from forwarding it to anyone else or printing it).
  7. A banner will appear at the top of your email saying "Encrypt-Only" or "Do Not Forward."
  8. Click Send.

Option 2: The "Keyword" Method (If the button is missing) ​

Many IT departments set up automatic rules that encrypt emails if you type a specific "magic word" in the subject line. This is useful if you are emailing from your phone where the Encrypt button might be hard to find.

  1. Open a New Email.
  2. In the Subject line, type your normal subject, but add [Encrypt] or [Secure] anywhere in the subject line.
    • Example: [Encrypt] Q3 Tax Documents for Review
  3. Hit Send. The company server will see the keyword and automatically encrypt the email before it leaves the building.
  4. (Check with your IT department to confirm exactly which keyword your company uses).

What Does the Recipient See? ​

When you send an encrypted email to someone outside your company (like a @gmail.com or @yahoo.com address), they will not see the message immediately.

  1. They will receive an email from you that says, "You have received a protected message."
  2. They must click a link that says Read the message.
  3. They will be taken to a secure Microsoft website.
  4. They can either sign in with their Microsoft/Google account, or click Sign in with a One-Time Passcode.
  5. If they choose the passcode, Microsoft will email them a 6-digit code. They type the code into the website, and the secure email (and attachments) will appear on their screen.

Troubleshooting ​

Symptom / ErrorPotential CauseSolution
I don't have an Encrypt button in OptionsLicense missingTry the Keyword method above. If that also fails, ask IT to enable message encryption for your account and tell them you need to send sensitive documents to an external recipient
Recipient says they can't open the emailBrowser issueTell them to try opening the "Read the message" link in an Incognito/Private browsing window
My email bounced back from DLPForgot to encryptThe automated system caught you sending sensitive data unencrypted. Open the draft, click Encrypt, and send again