How to Send an Encrypted Email in Outlook

To send an encrypted email in Outlook, start a new message, open the compose options, choose Encrypt, and send. If your version only shows Message options, use the S/MIME path instead. The exact clicks differ in new Outlook, classic Outlook, Outlook on the web, and Outlook.com.

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Oliver Jackson

Email Marketing Specialist

Michael Bodekaer
Reviewer

Founder, Board Member

Abraham Ranardo Sumarsono
Tester

Full Stack Engineer

Authored By Oliver Jackson Email Marketing Specialist

Oliver is an accomplished email marketing specialist with more than a decade's worth of experience. His strategic and creative approach to email campaigns has driven significant growth and engagement for businesses across diverse industries. A thought leader in his field, Oliver is known for his insightful webinars and guest posts, where he shares his expert knowledge. His unique blend of skill, creativity, and understanding of audience dynamics make him a standout in the realm of email marketing.

Reviewed By Michael Bodekaer Founder, Board Member

Michael Bodekaer is a recognized authority in email management and productivity solutions, with over a decade of experience in simplifying communication workflows for individuals and businesses. As the co-founder of Mailbird and a TED speaker, Michael has been at the forefront of developing tools that revolutionize how users manage multiple email accounts. His insights have been featured in leading publications like TechRadar, and he is passionate about helping professionals adopt innovative solutions like unified inboxes, app integrations, and productivity-enhancing features to optimize their daily routines.

Tested By Abraham Ranardo Sumarsono Full Stack Engineer

Abraham Ranardo Sumarsono is a Full Stack Engineer at Mailbird, where he focuses on building reliable, user-friendly, and scalable solutions that enhance the email experience for thousands of users worldwide. With expertise in C# and .NET, he contributes across both front-end and back-end development, ensuring performance, security, and usability.

How to Send an Encrypted Email in Outlook
How to Send an Encrypted Email in Outlook

To send an encrypted email in Outlook, start a new message, open the compose options, choose Encrypt , and send. If your version only shows Message options , use the S/MIME path instead. The exact clicks differ in new Outlook, classic Outlook, Outlook on the web, and Outlook.com. 2 3 5

This guide follows Microsoft’s current documented menu paths and recipient-access instructions. Account type, app version, and admin settings can change what appears in the compose window, so if you do not see Encrypt or Message options in a blank draft, skip to troubleshooting. 2 4 6 7

What’s new

Important: for “Encrypt Only” in classic Outlook, Microsoft documented a 2026 known issue tied to the older File route. If a recipient gets message_v2.rpmsg , update Outlook and resend from Options → Encrypt . 1

Table of contents

TL;DR

Quick answer: send encrypted email in Outlook by version

  • Use Options → Encrypt when your compose window shows it. 2 5
  • If your draft only shows Message options , use Encrypt this message (S/MIME) instead. 2 3
  • The exact clicks differ in new Outlook, classic Outlook, Outlook on the web, and Outlook.com. 2 3 5
  • Gmail, Yahoo, or another mail app recipients usually open the message in a browser and may use a one-time passcode. 4
  • Do not apply Microsoft Purview protection to a message that is already signed or encrypted with S/MIME. 2
  • If you do not see Encrypt , account type, app version, or admin settings may be the reason. 6 7 8
If you’re using Click this
New Outlook New mail → Options → Encrypt
New Outlook with S/MIME New mail → Options → More Options → Encrypt this message (S/MIME)
Classic Outlook New Email → Options → Encrypt
Outlook on the web, work or school New message → More options → Message options → Encrypt this message (S/MIME)
Outlook.com or new Outlook with Microsoft 365 Personal/Family New message / New mail → Options → Encrypt

New Outlook

Click this: New mail → Options → Encrypt

New Outlook with S/MIME

Click this: New mail → Options → More Options → Encrypt this message (S/MIME)

Classic Outlook

Click this: New Email → Options → Encrypt

Outlook on the web, work or school

Click this: New message → More options → Message options → Encrypt this message (S/MIME)

Outlook.com or new Outlook with Microsoft 365 Personal or Family

Click this: New message / New mail → Options → Encrypt

These are Microsoft’s current documented menu paths. The option you see can vary by Outlook version, account type, and admin settings. 2 3 5 6 7

Quick check: open a blank draft. If you see Options → Encrypt , use the standard path. If you see More options → Message options , use the S/MIME path. If you see neither, use the troubleshooting table below. 2 3 6

Before you start

1) Confirm your Outlook version

Check whether you are in new Outlook, classic Outlook, or Outlook on the web before you compose the real message. Microsoft is still moving some classic Outlook users to new Outlook in stages. 7

2) Check that encryption is available

Start a blank draft and look for Encrypt or More options → Message options . Outlook.com documents the built-in Encrypt menu for Microsoft 365 Personal and Family, while work or school accounts depend on your organization’s setup. Admins can also control whether the Encrypt button appears in Outlook on the web. 5 6

3) Set up S/MIME first if you need it

S/MIME requires a digital certificate . On Outlook on the web, you may also need the S/MIME control. New Outlook does not import digital certificates automatically. 3

4) Do not mix protection methods

Do not apply Microsoft Purview protection to a message that is already signed or encrypted with S/MIME. 2

How to send encrypted email in new Outlook

Use the standard path if your compose window shows Encrypt . If your organization requires S/MIME, use the second path below instead. 2 3

Standard Encrypt path

  1. Open a blank draft

    Click New mail .

  2. Open the encryption menu

    Click Options → Encrypt .

  3. Choose your setting

    Select Encrypt or Do Not Forward .

  4. Send the message

    Finish the draft and click Send . 2

S/MIME path in new Outlook

  1. Open the draft settings

    In your message, click Options → More Options .

  2. Turn on S/MIME encryption

    In Message options , check Encrypt this message (S/MIME) .

  3. Save the setting

    Click OK .

  4. Send the message

    Click Send . 2

If new Outlook warns that not all recipients can decrypt the message, fix the recipient list before sending. For external S/MIME messages, you also need the recipient’s certificate, and new Outlook does not import digital certificates automatically. 2 3

How to send encrypted email in classic Outlook

In classic Outlook, use the ribbon path instead of older File-dialog instructions. 1 2

How to send encrypted email in classic Outlook

  1. Open a new email

    Click New Email .

  2. Open the encryption menu

    On the ribbon, click Options → Encrypt .

  3. Choose your setting

    Select the option you want.

  4. Send the message

    Finish the draft and click Send . 2

How to send encrypted email in Outlook on the web

On the web, Microsoft documents an S/MIME path for work or school accounts and a built-in Encrypt menu for Outlook.com and Microsoft 365 Personal or Family accounts. 3 5

Work or school account

  1. Open a new message

    Click New message .

  2. Open message options

    Click More options → Message options .

  3. Turn on S/MIME encryption

    Check Encrypt this message (S/MIME) .

  4. Send the message

    Click Send . 2

If your compose bar shows a visible Encrypt button , you can use that shortcut instead. Outlook on the web warns you before sending if it cannot verify that every recipient can decrypt the message. 2 6

If Outlook on the web asks you to install S/MIME: go to Settings → Mail → S/MIME , click the install link, run the file, then close and reopen Outlook on the web. On Chrome, your work device may also need the required S/MIME browser policy from IT. 3

Outlook.com or new Outlook with Microsoft 365 Personal or Family

  1. Start a new message

    Open a blank draft.

  2. Open the encryption menu

    Click Options → Encrypt .

  3. Choose your setting

    Select Encrypt or Do Not Forward .

  4. Send the message

    Click Send . 5

If you change your mind before sending, switch back to No permission set . 5

What recipients see after you send

Recipient What they see What to tell them
Outlook or Microsoft 365 The message usually opens in Outlook, often with a restrictions banner. If it looks blank in conversation view, open it in a new window. 4 Ask them to open the email in a separate window if preview or conversation view looks wrong.
Gmail, Yahoo, or another mail app They usually get a Read the message link. They sign in with Google, Yahoo, or Microsoft, or request a one-time passcode. Each passcode expires after 15 minutes. 4 Tell them to click Read the message and request a fresh passcode if the first one expired.
S/MIME recipient They need the right certificate on their device. 2 If the recipient is outside your organization, you also need that person’s certificate before you send. 2

Outlook or Microsoft 365

What they see: The message usually opens in Outlook, often with a restrictions banner. If it looks blank in conversation view, open it in a new window. 4

What to tell them: Ask them to open the email in a separate window if preview or conversation view looks wrong.

Gmail, Yahoo, or another mail app

What they see: They usually get a Read the message link. They sign in with Google, Yahoo, or Microsoft, or request a one-time passcode. Each passcode expires after 15 minutes. 4

What to tell them: Tell them to click Read the message and request a fresh passcode if the first one expired.

S/MIME recipient

What they see: They need the right certificate on their device. 2

What to tell them: If the recipient is outside your organization, you also need that person’s certificate before you send. 2

Troubleshooting Outlook encrypted email problems

Symptom Likely cause Fix
Your menus do not match the steps. You are in a different Outlook version than you expected. Check whether you are in new Outlook, classic Outlook, or Outlook on the web before following the menu path. Microsoft is moving some Windows users from classic Outlook to new Outlook in stages. 7
You do not see Encrypt . Your account may not have encryption available, or the action may be hidden. On work or school accounts, ask IT to confirm your setup. On Outlook.com, go to Settings → Mail → Customize actions and add the action if it is available. 6 8
The recipient only sees message_v2.rpmsg . You used the older classic Outlook File route or hit the documented classic known issue. Update Outlook and resend from Options → Encrypt . 1
New Outlook warns that some recipients may not be able to decrypt. S/MIME cannot verify every recipient, or you are missing a needed certificate. Remove the problem recipient, install the right certificate, or use the standard Encrypt path if your account offers it. 2 3
Outlook on the web says you must install S/MIME first. The S/MIME control is not installed yet. Go to Settings → Mail → S/MIME , install the control, and reopen the web app before trying again. 3
Chrome still says S/MIME is not configured for this domain. Your work device may not have the required browser policy or domain setup. Try Edge first, or ask IT to apply the required S/MIME browser policy for your work domain. 3
A Gmail or Yahoo recipient cannot open the message. They skipped the browser flow or the passcode expired. Tell them to open the email, click Read the message , and request a fresh passcode if needed. 4
The message looks blank or broken in preview. Conversation view does not support encrypted messages. Open the email in a new window instead of relying on the preview pane alone. 4
You used S/MIME and Purview on the same draft. The message is using two protection methods. Remove one method, keep the other, and resend the message. 2

Your menus do not match the steps.

Likely cause: You are in a different Outlook version than you expected.

Fix: Check whether you are in new Outlook, classic Outlook, or Outlook on the web before following the menu path. Microsoft is moving some Windows users from classic Outlook to new Outlook in stages. 7

You do not see Encrypt .

Likely cause: Your account may not have encryption available, or the action may be hidden.

Fix: On work or school accounts, ask IT to confirm your setup. On Outlook.com, go to Settings → Mail → Customize actions and add the action if it is available. 6 8

The recipient only sees message_v2.rpmsg .

Likely cause: You used the older classic Outlook File route or hit the documented classic known issue.

Fix: Update Outlook and resend from Options → Encrypt . 1

New Outlook warns that some recipients may not be able to decrypt.

Likely cause: S/MIME cannot verify every recipient, or you are missing a needed certificate.

Fix: Remove the problem recipient, install the right certificate, or use the standard Encrypt path if your account offers it. 2 3

Outlook on the web says you must install S/MIME first.

Likely cause: The S/MIME control is not installed yet.

Fix: Go to Settings → Mail → S/MIME , install the control, and reopen the web app before trying again. 3

Chrome still says S/MIME is not configured for this domain.

Likely cause: Your work device may not have the required browser policy or domain setup.

Fix: Try Edge first, or ask IT to apply the required S/MIME browser policy for your work domain. 3

A Gmail or Yahoo recipient cannot open the message.

Likely cause: They skipped the browser flow or the passcode expired.

Fix: Tell them to open the email, click Read the message , and request a fresh passcode if needed. 4

The message looks blank or broken in preview.

Likely cause: Conversation view does not support encrypted messages.

Fix: Open the email in a new window instead of relying on the preview pane alone. 4

You used S/MIME and Purview on the same draft.

Likely cause: The message is using two protection methods.

Fix: Remove one method, keep the other, and resend the message. 2

Quick checklist before you send

Want a desktop email client for Windows or Mac? See how Mailbird handles security . 9

  • ☐ I confirmed whether I’m in new Outlook, classic Outlook, or Outlook on the web.
  • ☐ I know whether my path is Options → Encrypt or Message options → Encrypt this message (S/MIME) .
  • ☐ If I’m using S/MIME, my certificate is installed on this device.
  • ☐ If I’m sending S/MIME outside my organization, I have the recipient’s certificate.
  • ☐ I know what my recipient will see.
  • ☐ I tested the exact path before sending anything sensitive.

Frequently Asked Questions

Why don’t I see the Encrypt button in Outlook?

Your account may not have encryption available, your admin may control whether the option appears, or the action may be hidden in Outlook.com.

Sources: 6 8

Can I send an encrypted Outlook email to Gmail or Yahoo?

Yes. Those recipients usually receive a browser link and then sign in or use a one-time passcode.

Source: 4

Can recipients open an encrypted Outlook email without Outlook?

Usually yes through the browser flow. S/MIME can require certificate setup on the recipient side.

Sources: 2 4

Why does Outlook on the web ask me to install S/MIME?

That account is using the web S/MIME path, which needs the S/MIME control before you can sign or encrypt messages.

Source: 3

Why did a recipient get message_v2.rpmsg ?

Microsoft documented a classic Outlook “Encrypt Only” issue tied to the older File route. Use Options → Encrypt and resend after updating Outlook.

Source: 1

Do attachments stay encrypted?

For Outlook.com with Microsoft 365 Personal or Family, Microsoft documents different download behavior for attachments under Encrypt and Do Not Forward .

Source: 5

Can I make encrypted email the default in Outlook?

Yes, for S/MIME. In new Outlook or Outlook on the web, use Settings → Mail → S/MIME . In classic Outlook, use File → Options → Trust Center → Trust Center Settings → Email Security .

Sources: 2 3