Sideload Outlook add-ins for testing

You can use sideloading to install an Outlook add-in for testing without having to first put it in an add-in catalog.

Note You can also sideload add-ins for other Office suite applications. For more information, see Sideload Office Add-ins for testing.

To sideload Outlook add-ins

  1. Go to Outlook Web App.

  2. Choose the gear icon in the top-right section and select Manage add-ins.

    Outlook Web App screenshot pointing to Manage add-ins option

  3. On the Manage add-ins page, select the + icon and then select Add from a file.

    Manage add-ins screenshot pointing to Add from a file option

  4. Locate the manifest file for your custom add-in and install it. Accept all prompts during the installation.

When that's done, select an existing email and you will see a horizontal bar below the email header that includes the add-in. Next, create an email, and then choose the Add-ins (or Apps) menu item to get the task pane to appear. Select the add-in and see it appear in the task pane.