How to Send Secure Email in Outlook 365

How to Send Secure Email in Outlook 365 (Very Detailed Step-by-Step Guide)

Sending an email feels simple—but standard emails are not secure. Anyone intercepting the message can read the content, download attachments, or forward sensitive data.

Microsoft Outlook 365 solves this with built-in email encryption and access controls. You don’t need third-party tools, plugins, or coding knowledge.

This guide explains every secure email method in Outlook 365, step by step, with real-world examples.

Step 1: Understand What “Secure Email” Means in Outlook 365

Before using the tools, it’s important to know what Outlook actually protects.

When you send a secure email in Outlook 365, it can:

• Encrypt the message so only the recipient can read it

• Prevent forwarding, copying, or printing

• Protect attachments from unauthorized access

• Require identity verification for external users

• Allow access revocation later (via OneDrive links)

Microsoft provides this through Microsoft Purview Message Encryption.

Step 2: Check If Your Outlook 365 Account Supports Encryption

Most Outlook 365 accounts already support encryption, including:

• Microsoft 365 Business

• Microsoft 365 Enterprise

• Outlook.com (limited features)

1. Open Outlook

2. Click New Email

3. Click Options

4. Look for Encrypt

If you see Encrypt, you’re good to go.

Step 3: Send a Basic Encrypted Email (Beginner Method)

This is the easiest and safest way to send secure email.

1. Open Outlook 365

2. Click New Email

3. Enter the recipient’s email address

4. Write your message

5. Click Options in the top menu

6. Click Encrypt

7. Choose Encrypt

8. Click Send

Your email is now encrypted.

1. Go to outlook.office.com

2. Click New mail

3. Write your email

4. Click the three dots (⋯)

5. Select Encrypt

6. Send the email

Step 4: What Happens After You Send an Encrypted Email

• Email opens normally

• Encryption happens automatically in the background

• No extra steps required

• They receive a secure message

• They must:

  • Sign in with Microsoft
    or

  • Use a one-time passcode sent to their email

This ensures only the intended recipient can read the message.

Step 5: Use “Do Not Forward” for Maximum Security

This option is perfect for confidential emails.

• Blocks forwarding

• Disables copy/paste

• Prevents printing

• Restricts downloads (attachments stay protected)

1. Click New Email

2. Write your message

3. Click Options

4. Click Encrypt

5. Select Do Not Forward

6. Send the email

Use this for:

• Contracts

• Legal documents

• Salary details

• Client agreements

• Sensitive reports

Step 6: Secure Attachments Properly (Most Important Step)

Attachments are the most common data-leak source.

Option A: Encrypt Attachments Inside Email

1. Attach files normally

2. Enable Encrypt or Do Not Forward

3. Send

Attachments inherit the same protection as the email.

Option B: Use OneDrive Secure Links (Best Practice)

This gives you full control over files.

1. Upload the file to OneDrive

2. Right-click the file → Share

3. Click Link settings

4. Configure:

   • View only or edit

   • Expiration date

   • Password (optional)

5. Copy the link

6. Paste it into your Outlook email

7. Enable Encrypt

You can revoke access anytime.

Step 7: Use Password Protection for Extra Security (Optional)

For highly sensitive data, add another layer.

• Password-protected PDF

• Encrypted ZIP file (AES-256)

⚠️ Never send the password in the same email

Send the password via:

• SMS

• Phone call

• Secure messaging app

Step 8: How to Confirm Your Email Is Secure Before Sending

Before clicking Send:

• Check Encrypt is selected

• Look for the lock icon 🔒

• Outlook shows a security confirmation message

After sending:

1. Open Sent Items

2. Open the email

3. You’ll see an encryption notice

Step 9: Encrypt Replies and Email Threads

Encryption does not always auto-apply to replies.

• Always click Encrypt again when replying

• Especially important for:

  • Long conversations

  • Multiple recipients

  • External users

Step 10: Common Secure Email Mistakes to Avoid

• Sending passwords in plain text
• Forgetting to encrypt attachments
• Assuming HTTPS means encrypted email
• Sending sensitive data to the wrong recipients
• Using screenshots instead of secure files

Step 11: Is Outlook 365 Secure Email Compliant?

Yes—when used properly.

Supports:

• GDPR

• HIPAA

• SOC 2

• ISO 27001

Compliance depends on:

• Encryption enabled

• Access controls used

• Secure storage practices

Step 12: When to Use Each Security Method

Final Conclusion

Outlook 365 already includes enterprise-grade email security, but most users never turn it on.

If you follow these steps:

• Your emails stay private

• Your attachments stay protected

• Your clients trust your communication

• Your business stays compliant

For 90% of users, simply using Encrypt or Do Not Forward is enough.