how to encrypt email outlook 365

How to Encrypt Email in Outlook 365: A Comprehensive Guide

Email encryption is a crucial aspect of maintaining the security and privacy of your communications. With the increasing prevalence of cyber threats and data breaches, it is essential to take proactive measures to protect sensitive information. Microsoft Outlook 365, a popular email client used by millions of individuals and businesses worldwide, offers robust encryption features to safeguard your emails from unauthorized access. In this article, we will explore the various methods and best practices for encrypting emails in Outlook 365.

Understanding Email Encryption

Email encryption is the process of encoding the content of an email message to prevent unauthorized individuals from accessing or reading its contents. Encryption ensures that only the intended recipient can decrypt and view the message, providing an additional layer of security to sensitive information. By encrypting your emails, you can protect confidential data such as financial information, personal details, and trade secrets from falling into the wrong hands.

There are two primary types of email encryption: symmetric encryption and asymmetric encryption. Symmetric encryption uses a single key to both encrypt and decrypt the message, while asymmetric encryption uses a pair of keys: a public key for encryption and a private key for decryption. Outlook 365 supports both types of encryption, allowing users to choose the method that best suits their needs.

Encrypting Emails in Outlook 365

Outlook 365 provides several options for encrypting emails, ensuring that your messages remain secure and confidential. Let’s explore these options in detail:

1. Encrypting Individual Emails

If you only need to encrypt specific emails containing sensitive information, Outlook 365 allows you to encrypt individual messages on a case-by-case basis. Here’s how you can encrypt an individual email:

  1. Compose a new email in Outlook 365.
  2. Click on the “Options” tab in the ribbon at the top of the email composition window.
  3. In the “More Options” group, click on the “Encrypt” button.
  4. Choose the encryption option that suits your needs. Outlook 365 offers two encryption options: S/MIME encryption and Office 365 Message Encryption.
  5. If you choose S/MIME encryption, ensure that the recipient has a valid S/MIME certificate installed on their email client.
  6. If you choose Office 365 Message Encryption, you can set additional permissions such as preventing the recipient from forwarding or printing the email.
  7. Finish composing your email and click on the “Send” button.

By encrypting individual emails, you can have granular control over the security of your messages. However, this method requires manual intervention for each email, which may not be practical for large volumes of sensitive communications.

2. Encrypting Emails with Sensitivity Labels

If you frequently send emails containing sensitive information, Outlook 365 provides a more automated approach to email encryption using sensitivity labels. Sensitivity labels allow you to classify emails based on their level of sensitivity and automatically apply encryption and other security settings. Here’s how you can encrypt emails using sensitivity labels:

  1. Open Outlook 365 and click on the “New Email” button to compose a new email.
  2. In the email composition window, click on the “Options” tab in the ribbon.
  3. In the “Sensitivity” group, click on the “Sensitivity” dropdown menu.
  4. Select the appropriate sensitivity label for your email. Outlook 365 offers several predefined sensitivity labels such as “Personal,” “Confidential,” and “Top Secret.” You can also create custom sensitivity labels tailored to your organization’s needs.
  5. Finish composing your email and click on the “Send” button.

When you apply a sensitivity label to an email, Outlook 365 automatically encrypts the message based on the encryption settings associated with the label. This ensures consistent and streamlined encryption for sensitive communications, reducing the risk of human error.

3. Encrypting Emails with Rights Management Services (RMS)

For organizations that require advanced encryption capabilities and control over their sensitive communications, Outlook 365 integrates with Microsoft’s Rights Management Services (RMS). RMS allows you to apply persistent encryption to emails, ensuring that the message remains encrypted even after it leaves your organization’s network. Here’s how you can encrypt emails using RMS:

  1. Ensure that your organization has an active subscription to Microsoft’s Rights Management Services.
  2. Compose a new email in Outlook 365.
  3. Click on the “Options” tab in the ribbon at the top of the email composition window.
  4. In the “Permissions” group, click on the “Encrypt” button.
  5. Choose the appropriate RMS template for your email. RMS templates define the encryption and usage rights for the email, allowing you to control who can access, forward, or print the message.
  6. Finish composing your email and click on the “Send” button.

By leveraging RMS, organizations can enforce strict encryption policies and maintain control over their sensitive communications, even when emails are shared with external parties. This level of encryption is particularly valuable for industries such as healthcare, finance, and legal, where regulatory compliance and data protection are paramount.

Best Practices for Email Encryption in Outlook 365

While Outlook 365 provides robust encryption features, it is essential to follow best practices to maximize the effectiveness of your email encryption efforts. Here are some tips to enhance the security of your encrypted emails:

1. Use Strong Passwords

When encrypting emails in Outlook 365, it is crucial to use strong passwords to protect your encryption keys. Weak passwords can be easily cracked by attackers, rendering your encryption efforts futile. Ensure that your passwords are at least eight characters long and include a combination of uppercase and lowercase letters, numbers, and special characters.

2. Regularly Update Outlook 365

Microsoft regularly releases updates and patches for Outlook 365 to address security vulnerabilities and improve the overall performance of the software. It is crucial to keep your Outlook 365 installation up to date to benefit from the latest security enhancements. Enable automatic updates or regularly check for updates manually to ensure that you are running the latest version of Outlook 365.

3. Educate Users on Email Security

Human error is one of the leading causes of data breaches and email security incidents. It is essential to educate users on email security best practices, such as avoiding clicking on suspicious links or downloading attachments from unknown sources. Conduct regular training sessions and provide resources to help users understand the importance of email encryption and how to use encryption features effectively.

4. Enable Two-Factor Authentication

Two-factor authentication adds an extra layer of security to your Outlook 365 account by requiring users to provide a second form of verification, such as a unique code sent to their mobile device, in addition to their password. Enabling two-factor authentication reduces the risk of unauthorized access to your email account, further protecting your encrypted emails.

5. Regularly Backup Encrypted Emails

While encryption provides robust protection for your emails, it is essential to have backups in case of unforeseen circumstances such as hardware failures or accidental deletion. Regularly backup your encrypted emails to a secure location, either on-premises or in the cloud, to ensure that you can recover your data in the event of a loss.


Q1: Can I encrypt attachments in Outlook 365?

A1: Yes, Outlook 365 allows you to encrypt attachments along with your emails. When you encrypt an email, any attachments included in the email are also encrypted, ensuring that the entire message remains secure.

Q2: Can I encrypt emails sent to recipients using other email clients?

A2: Yes, Outlook 365 supports industry-standard encryption protocols such as S/MIME and Office 365 Message Encryption, which are compatible with most email clients. However, it is essential to ensure that the recipient’s email client supports the encryption method you choose.

Q3: Can I revoke access to an encrypted email after it has been sent?

A3: If you encrypt an email using Microsoft’s Rights Management Services (RMS), you can revoke access to the email even after it has been sent. This feature provides an additional layer of control over your sensitive communications, allowing you to maintain confidentiality even if the email falls into the wrong hands.


Email encryption is a critical aspect of maintaining the security and privacy of your communications. Outlook 365 offers robust encryption features, allowing users to encrypt individual emails, apply sensitivity labels, and leverage Microsoft’s Rights Management Services (RMS) for advanced encryption capabilities. By following best practices and implementing encryption measures, you can protect sensitive information from unauthorized access and mitigate the risk of data breaches. Remember to use strong passwords, regularly update Outlook 365, educate users on email security, enable two-factor authentication, and backup encrypted emails to ensure comprehensive protection for your communications. With the increasing prevalence of cyber threats, it is essential to prioritize email encryption to safeguard your sensitive information and maintain the trust of your clients and partners.


I am a technology writer specialize in mobile tech and gadgets. I have been covering the mobile industry for over 5 years and have watched the rapid evolution of smartphones and apps. My specialty is smartphone reviews and comparisons. I thoroughly tests each device's hardware, software, camera, battery life, and other key features. I provide in-depth, unbiased reviews to help readers determine which mobile gadgets best fit their needs and budgets.

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