Email remains one of the most popular ways we share sensitive information like contracts, invoices, internal documents, and personal details. However, the reality is that standard emails aren’t inherently secure. They can be intercepted, accessed through compromised accounts, or accidentally forwarded, leading to potential leaks.  


That’s where email encryption steps in. 

If you want to encrypt email in Outlook to keep your messages private and readable only by the right people, encryption gives you that extra layer of protection. The good news? You don't need to be "tech-savvy" to use it.  

Let’s break down how Outlook email encryption works, why you should use it, and step-by-step methods you can follow right away. 


What Email Encryption Actually Does


Think of encryption as locking your email inside a sealed box before it leaves your computer. Only the person with the right key (your recipient) can open it. Even if someone intercepts the email mid-route, all they see is scrambled, unreadable text. 

Outlook gives you two main ways to encrypt emails: 

  1. Microsoft 365 Message Encryption (Easiest)
  1. S/MIME Encryption (More advanced, certificate-based) 

You don’t have to know the deep technical side, just pick the option that works best for your setup. 


Why Encrypting Your Outlook Emails Matters


Email may seem like a casual way to communicate, but it’s actually one of the most vulnerable channels we use daily. By encrypting your Outlook emails, you not only protect yourself but also safeguard the people you’re in touch with and the reasons for doing so go well beyond just “extra security.” 

Let’s look at a few real-life situations where encryption really makes a difference: 


Sharing Sensitive Information 

Whether it’s client details, financial documents, legal files, internal reports, or personal data, unencrypted emails can be surprisingly easy to intercept. Encryption ensures that only the person you intend to receive your message can actually read it. 


Privacy Laws and Security Regulations 

Fields like healthcare, finance, legal services, and government have to comply with strict regulations such as GDPR, HIPAA, PCI-DSS, or ISO standards. Using encrypted email helps you meet these requirements and steer clear of hefty fines. 


Avoid Accidental Leaks 

A simple typo in an email address, a forwarded message, or a shared inbox can lead to sensitive information being exposed in no time. Encryption provides an extra layer of security, even when human mistakes happen.


Value Secure and Private Communication 

Not every email is a matter of life and death, but knowing that your messages aren’t accessible to servers, hackers, or anyone eavesdropping on a Wi-Fi network gives you genuine peace of mind. 

And if you’re running a business, using encrypted communication sends a strong message.  It shows clients and partners that you genuinely care about their privacy. In today’s world, where security is a top concern, that kind of trust isn’t just a nice perk; it’s a real competitive edge.  


How to Encrypt Email in Outlook Using Microsoft 365 Message Encryption


This is the easiest method for most users because it’s built into Outlook (desktop, web, and mobile) when you're using a Microsoft 365 business or enterprise plan. 


Before you start, you need: 

  •  A Microsoft 365 subscription that supports encryption. 
  •   Outlook desktop or Outlook on the web. 

A. Encrypt an Email in Outlook Desktop 

  1. Open Outlook and click New Email. 
  1. Compose your message as usual. 
  1. Go to the Options tab at the top of the message window. 
  1. In the Permission or Encrypt section of the ribbon (usually toward the right side), click Encrypt. 

  1. Choose your preferred option: 
  1. Encrypt Only 
  1. Do Not Forward 
  1. Encrypt – Confidential 
  1. Encrypt – Confidential \ All Employees 
  1. Hit Send. Outlook does the rest. 

Your recipient will either open the email directly or through a secure Microsoft portal.


B. Encrypt an Email in Outlook Web (Outlook.com or Outlook Online) 

  1. Click New Message. 
  1. Write your email. 
  1. At the top, click the Encrypt button (it may appear under three dots: More options). 
  1. Choose: 
  1. Encrypt Only 
  1. Do Not Forward 
  1. Send your message. 

Your recipient will receive a protected email with instructions on how to view it securely. 


How to Encrypt Emails Using S/MIME in Outlook


This method is popular in organizations with strict security policies. It uses digital certificates like a digital ID to encrypt and sign emails.

Before you start, you need: 

  • An S/MIME certificate from a trusted provider. 
  • Certificate installed on your computer. 
  • Your recipient must also have an S/MIME certificate. 
  • You must exchange digital signatures with each other. 

This method is more secure but needs a setup. 


A. Enable S/MIME in Outlook Desktop 

  1. Get and install your S/MIME certificate. 
  1. Open Outlook > File > Options. 
  1. Go to Trust Center > Trust Center Settings.
  1. Click on Email Security. 
  1. Under Encrypted Email, check: 
  1. Encrypt contents and attachments for outgoing messages (optional) 
  1. Or select Settings to choose your S/MIME certificate manually 
  1. Save changes. 

Now, when you send an email to someone who also has an S/MIME certificate, Outlook can encrypt it automatically. 


B. Enable S/MIME in Outlook Web 

Some organizations allow S/MIME in the web app. 

  1. Open the Outlook Web. 
  1. Go to Settings (gear icon). 
  1. Search for S/MIME in the settings panel. 
  1. Download and install the S/MIME extension if prompted. 

After installation, you’ll see signing and encryption options inside the email window.


How to Know Your Email Is Encrypted


Encrypted messages often show: 

  • A lock icon in the subject line or near the sender’s name. 
  • A message banner stating that the email is protected. 
  • Restricted forwarding options. 
  • Opening instructions for external recipients. 

If you see any of the above, your email encryption is active. 


When You Should Definitely Encrypt Outlook Emails


Learning when to encrypt email in Outlook is just as important as knowing how to do it. Here are situations where encryption is strongly recommended:  

  • Whenever you are sharing financial information. 
  • When you share contracts or legal documents with another person or organization. 
  • If you are sending personal data about a client/employee.  
  • When you are discussing internal business issues, that may be considered sensitive. 
  • When you communicate with your business partners that are outside of your company. 

If you’d hesitate before forwarding the email, it’s a good candidate for encryption. 


Troubleshooting: Common Encryption Issues in Outlook


Even with strong encryption tools, Outlook can sometimes show errors or behave differently than expected. Here are some quick troubleshooting tips to help you fix common issues without derailing your workflow.  


1. Recipient can’t open the encrypted message 

They may need: 

  • A Microsoft account. 
  • To verify their identity. 
  • An S/MIME certificate (for S/MIME emails). 

2. Encrypt button missing 

This may happen if: 

  • Your Microsoft 365 plan doesn’t support encryption. 
  • Admin hasn’t enabled the feature. 

3. S/MIME not working 

When S/MIME is not working properly, check: 

  • Your certificate installation. 
  • Whether your recipient has a certificate. 
  • That both of you exchanged signed emails first. 

Best Practices for Email Encryption


Email encryption is most effective when it’s combined with smart habits. These practices help keep your messages private, your data secure, and your communication professional.  

  • Make sure to encrypt anything that includes sensitive, private, or regulated information.  
  • Educate your teams when encryption is essential.  
  • Use “Do Not Forward” for confidential emails within your organization. 
  • Never send passwords, bank details, or IDs without proper protection.  
  • Pair encryption with strong password practices and multi-factor authentication for added security.  

Combine encryption with other professional email practices. When you add signature in Outlook to your encrypted messages, you create a complete, trustworthy communication package that shows recipients you take both security and professionalism seriously.  


Final Thoughts


Once you familiarize yourself with your options, learning how to encrypt email in Outlook is pretty straightforward. Whether you choose the basic Microsoft 365 encryption or a certificate-based method like S/MIME, both offer a robust layer of security for your communications.