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Microsoft Outlook Add-in

Encrypt your email attachments with seamless Outlook integration

With the Trebuchet Microsoft® Outlook® add-in you can send email attachments with full end-to-end encryption and complete privacy and peace of mind.

A simple click automatically converts your file attachments to a secure sharing link.

Supports Outlook on Windows, Outlook on MacOS and Outlook on the Web

How to install the Trebuchet Outlook add-in

Install the Outlook add-in in a few simple steps

For M365 Administrators

M365 Administrators can deploy the add-in automatically for all users using Microsoft 365 Centralized Deployment.

  1. Visit the M365 Exchange Admin Center
  2. Add a new Add-in, selecting 'Add from URL'
  3. Enter the manifest URL:
    (note for Enterprise customers replace '' with the root of your Trebuchet domain)

For Individuals

Individuals can install the Outlook add-in for their email account. The add-in will then be available in the desktop Outlook application and in Outlook on the web.

  1. Open 'Get Add-ins'. This is in a different place depending on which Outlook you are using:
    - Outlook App in Windows: the button is in the ribbon bar at the top
    - Outlook App on MacOS: open a new email, and the button is in the menu at the top
    - Outlook on the Web: open a new email, and the button is in the menu at the bottom
  2. Select 'My add-ins' in the left menu
  3. Scroll down to the 'Custom Addins' section
  4. Select 'Add a custom add-in, selecting 'Add from URL'
  5. Enter the manifest URL: