If you’re using the new version of Outlook or Outlook Web, please follow this installation procedure instead : How to Install Secure Exchanges on Outlook Web ?
Before you begin: Make sure to close Microsoft Outlook.
Important: Do not run the installation in admin mode.1.2. Click “Download” to install the required plugins.

After downloading, open your Downloads folder.
You should see two files:
setup.exe
file.zip
Double-click on the .zip file, then open SecureExchangesOASF.msi.
If a security message appears:
Click “More info”
Then click “Run anyway”
The installer will open. Click “Next” through each step until the installation is complete.

Once the installation is complete, continue with the next steps to activate your license.
2.1. Once the plugin is installed, open your Outlook mailbox.

2.2. Click on the “Secure Exchanges” tab.
2.3. If your license is inactive, click “Get my licence back.”
2.4. Verify your email address, complete the CAPTCHA to confirm you’re not a robot, then click “Send.”
2.5. Confirm the activation of your license on your device by selecting “Yes.”
2.6. Go back to the “Secure Exchanges” tab.
Your license status should now indicate “Active.”
Congratulations! You’ve successfully activated your Secure Exchanges license and can now protect your data transfers securely.