How to Send Secure Email in Outlook

Your Guide to Encrypting Messages

Email remains a cornerstone of professional and personal interactions. However, this convenience comes with the ever-present threat of data breaches and unauthorized access to sensitive information.

Businesses can protect themselves against such sophisticated attacks by adopting encryption solutions from various email solution providers. Microsoft Outlook – the widely used tool - offers robust solutions for safeguarding your emails through encryption.

In this article, we will touch upon how Microsoft does that and introduce some viable alternatives for those seeking additional security.

What is Email Encryption?

Email encryption is the process of converting the content of an email message into a code to prevent unauthorized access. In simpler terms, it locks your message in a digital safe, ensuring that only the intended recipient can decipher its contents.

Email security relies on encryption, which involves complex algorithms and cryptographic keys to transform plain text into an unreadable format during transmission. Only someone with the correct decryption key can read the message in its original form.

What is Microsoft Outlook?

Microsoft Outlook is a widely used email solution, a part of the Microsoft Office suite. It offers a range of features for managing emails, calendars, tasks, and contacts. Individuals and organizations alike favour Outlook for its user-friendly interface and seamless integration with other Microsoft products.

How is Outlook Encrypted?

Microsoft Outlook employs several security measures to ensure the confidentiality of your emails:

  1. Transport Layer Security (TLS): Outlook uses TLS to encrypt email communications during transmission. When you send an email from Outlook to a recipient using a compatible email service, Outlook secures the message as it travels through the internet.
  2. S/MIME (Secure/Multipurpose Internet Mail Extensions): S/MIME is a protocol supported by Outlook that allows you to digitally sign and encrypt your emails. It requires the use of digital certificates to verify the sender's identity and encrypt the message content.
  3. Office 365 Message Encryption: For businesses using Office 365, Outlook offers an additional layer through Office 365 Message Encryption. This feature allows you to send secure emails to anyone, regardless of their email provider. Recipients receive a notification with instructions on how to decrypt the message securely.

Importance of Encrypted Email

  1. Confidentiality: It guarantees that only authorized recipients can access the message content, keeping your sensitive information private.
  2. Integrity: It verifies that the message hasn't been tampered with during transit, ensuring the information's accuracy and reliability.
  3. Compliance: Many industries and organizations are legally obligated to protect sensitive data through encryption to comply with data privacy regulations.
  4. Protection Against Cyber Threats: Email is a prime target for cyberattacks. It provides a defense against interception and data theft.

How to Send a Secure Email in Outlook?

Now that we understand the importance of encrypted email, let's explore how to send secure emails using Microsoft Outlook via few simple steps:

Step 1: Set Up S/MIME

  1. To use S/MIME, you need a digital certificate issued by a trusted certificate authority. If you don't have one, you can obtain it through your organization's IT department or a certificate provider.
  2. In Outlook, go to "File" > "Options" > "Trust Center" > "Trust Center Settings" > "Email Security." Here, you can import your digital certificate.

Step 2: Compose Your Email

  1. Start a new email in Outlook.
  2. In the email window, click on "Options."
  3. In the "Security Settings" section, ensure that "Encrypt message contents and attachments" is selected.
  4. Compose your email as usual and click "Send."

The intended recipient can now decrypt your email using the corresponding decryption key, which will now use S/MIME.

Step 3: Office 365 Message Encryption

If you are using Office 365 and need to send secure emails to recipients outside your organization, follow these steps:

  1. Compose your email in Outlook.
  2. In the email window, click on "Protect" in the ribbon.
  3. Select "encrypt" and follow the prompts to set the encryption level and add any necessary permissions.
  4. Click "Send."

Recipients can securely access your email, even if they don't use Outlook or Office 365.

Best Alternatives to Outlook for Secure Email

While Microsoft Outlook offers robust email encryption features, you can also explore alternative email clients/solution providers that offer additional enhanced features. Here are a few considerations while doing so:

  • Many secure email providers offer robust security and encryption levels depending on the business requirements. For example, one could choose a secure email gateway or a simple encryption service.
  • Few robust applications or add-ins run inside your Outlook inbox and provide real-time security, privacy, and audit trails with proof of sending, reading, and viewing.
  • A secure email means not only creating it securely but also delivering it securely. Majority of the email cybercrimes begin when the email in transit is not secure and easily eavesdropped on by criminals.

It’s critical for businesses dealing with sensitive information on a daily basis to use a reliable, affordable, and advanced email encryption or protection solution.


Q: Is Outlook encryption sufficient for my business's email security?

Outlook encryption is robust and suitable for many business needs. However, depending on your industry and compliance requirements, you may need to consider additional security measures or advanced alternatives.

Q: Are encrypted emails completely immune to hacking?

While encryption significantly enhances security, no system is entirely immune to hacking. It's crucial to stay vigilant, keep software up to date, and follow best practices for cybersecurity.

Q: Can I send encrypted emails to recipients who don't use Outlook?

Yes. Various email clients support the S/MIME protocol for encryption, which Outlook uses. However, the recipient's email client must also support S/MIME for them to decrypt and read the encrypted email.