Learn how to send encrypted emails in Outlook using S/MIME and Microsoft Purview, with expert troubleshooting for 2026.
As a Tech Specialist who has spent years bridging the gap between high-level development and user experience, I’ve seen the “security-usability” trade-off play out countless times. In 2026, where data breaches are no longer a “maybe” but a “when,” sending a standard plaintext email is the digital equivalent of sending a postcard – anyone in the delivery chain can read it.
If you’re looking to send encrypted emails in Outlook, you’re likely balancing the need for compliance (HIPAA, GDPR) with the need for speed. This guide breaks down the two primary protocols – Microsoft Purview and S/MIME – and provides the actionable steps to secure your inbox today.
M365 Message Encryption vs. S/MIME: Which One Do You Need?
Before we dive into the how, we need to clarify the what. Not all encryption is created equal.
| Feature | Microsoft Purview (M365) | S/MIME |
|---|---|---|
| Ease of Use | High (No certificates needed) | Medium (Requires Digital ID) |
| Recipient Compatibility | Works with Gmail, Yahoo, etc. | Both parties need S/MIME setup |
| Security Level | Portal-based (Microsoft holds keys) | Peer-to-Peer (You hold keys) |
| Best For | Casual business & external clients | High-security govt/enterprise |
Method 1: How to Send Encrypted Email in Outlook (M365/Purview)
This is the standard for most Microsoft 365 Personal, Family, and Business subscribers. It doesn’t require the recipient to have special software.
On Outlook Desktop (Classic & New)
- Compose: Click New Email.
- Navigate: Go to the Options tab.
- Encrypt: Select the Encrypt button.
- Choose Permission: *Encrypt-Only: Scrambles the message.
- Do Not Forward: Prevents the recipient from copying or forwarding the content.
- Send: Complete your message and hit Send.
On Outlook Web (OWA)
- Click New Mail.
- Select Options > Encrypt.
- Choose your desired restriction (Encrypt or Do Not Forward).
- Specialist Tip: If you don’t see the button, click the three dots (…) or check your “Customize Actions” settings.
Method 2: The S/MIME Protocol (End-to-End Encryption)
For my fellow developers and tech specialists, S/MIME is the “Gold Standard.” It uses a Digital ID (certificate) to verify your identity and encrypt the payload.
- Obtain a Certificate: You must have a valid Digital ID from a Certificate Authority (CA).
- Install it: In Outlook, go to File > Options > Trust Center > Trust Center Settings > Email Security.
- Configure: Under Encrypted email, click Settings and select your S/MIME certificate.
- Send: When composing, go to Options > Permissions and select Encrypt with S/MIME.
Troubleshooting: Why is the Encrypt Button Missing?
In my consulting work with Techrytr, the “missing button” is the #1 complaint. Here is how to fix it:
- Licensing Check: Built-in encryption (Purview) usually requires a Microsoft 365 Business Premium, E3, or E5 license. If you are on a basic “Business Standard” license, you may need an add-on.
- The PowerShell Fix (For Admins): If you’re an admin and the button is gone for your whole team, run this command in Exchange Online PowerShell:
Set-IRMConfiguration -SimplifiedClientAccessEnabled $true - S/MIME Conflict: If you have S/MIME enabled but no certificate installed, the “Encrypt” button may be grayed out. Uncheck S/MIME in the message options to restore Purview encryption.
Specialist Insight: The 2026 Security Landscape
While the methods above are robust, the future of email security lies in Sensitivity Labels. In 2026, many organizations are moving away from manual encryption. Instead, you label an email as “Confidential,” and Outlook automatically applies the encryption rules based on your company’s policy.
If you are a content strategist or a business owner, I highly recommend setting up these labels. It removes the human error factor – your team doesn’t have to remember to “send encrypted email outlook”; the system does it for them based on the content.
Learn how to send encrypted emails in Outlook using S/MIME and Microsoft Purview, with expert troubleshooting for 2026.
As a Tech Specialist who has spent years bridging the gap between high-level development and user experience, I’ve seen the “security-usability” trade-off play out countless times. In 2026, where data breaches are no longer a “maybe” but a “when,” sending a standard plaintext email is the digital equivalent of sending a postcard – anyone in the delivery chain can read it.
If you’re looking to send encrypted emails in Outlook, you’re likely balancing the need for compliance (HIPAA, GDPR) with the need for speed. This guide breaks down the two primary protocols – Microsoft Purview and S/MIME – and provides the actionable steps to secure your inbox today.
M365 Message Encryption vs. S/MIME: Which One Do You Need?
Before we dive into the how, we need to clarify the what. Not all encryption is created equal.
| Feature | Microsoft Purview (M365) | S/MIME |
|---|---|---|
| Ease of Use | High (No certificates needed) | Medium (Requires Digital ID) |
| Recipient Compatibility | Works with Gmail, Yahoo, etc. | Both parties need S/MIME setup |
| Security Level | Portal-based (Microsoft holds keys) | Peer-to-Peer (You hold keys) |
| Best For | Casual business & external clients | High-security govt/enterprise |
Method 1: How to Send Encrypted Email in Outlook (M365/Purview)
This is the standard for most Microsoft 365 Personal, Family, and Business subscribers. It doesn’t require the recipient to have special software.
On Outlook Desktop (Classic & New)
- Compose: Click New Email.
- Navigate: Go to the Options tab.
- Encrypt: Select the Encrypt button.
- Choose Permission: *Encrypt-Only: Scrambles the message.
- Do Not Forward: Prevents the recipient from copying or forwarding the content.
- Send: Complete your message and hit Send.
On Outlook Web (OWA)
- Click New Mail.
- Select Options > Encrypt.
- Choose your desired restriction (Encrypt or Do Not Forward).
- Specialist Tip: If you don’t see the button, click the three dots (…) or check your “Customize Actions” settings.
Method 2: The S/MIME Protocol (End-to-End Encryption)
For my fellow developers and tech specialists, S/MIME is the “Gold Standard.” It uses a Digital ID (certificate) to verify your identity and encrypt the payload.
- Obtain a Certificate: You must have a valid Digital ID from a Certificate Authority (CA).
- Install it: In Outlook, go to File > Options > Trust Center > Trust Center Settings > Email Security.
- Configure: Under Encrypted email, click Settings and select your S/MIME certificate.
- Send: When composing, go to Options > Permissions and select Encrypt with S/MIME.
Troubleshooting: Why is the Encrypt Button Missing?
In my consulting work with Techrytr, the “missing button” is the #1 complaint. Here is how to fix it:
- Licensing Check: Built-in encryption (Purview) usually requires a Microsoft 365 Business Premium, E3, or E5 license. If you are on a basic “Business Standard” license, you may need an add-on.
- The PowerShell Fix (For Admins): If you’re an admin and the button is gone for your whole team, run this command in Exchange Online PowerShell:
Set-IRMConfiguration -SimplifiedClientAccessEnabled $true - S/MIME Conflict: If you have S/MIME enabled but no certificate installed, the “Encrypt” button may be grayed out. Uncheck S/MIME in the message options to restore Purview encryption.
Specialist Insight: The 2026 Security Landscape
While the methods above are robust, the future of email security lies in Sensitivity Labels. In 2026, many organizations are moving away from manual encryption. Instead, you label an email as “Confidential,” and Outlook automatically applies the encryption rules based on your company’s policy.
If you are a content strategist or a business owner, I highly recommend setting up these labels. It removes the human error factor – your team doesn’t have to remember to “send encrypted email outlook”; the system does it for them based on the content.