Install the Rainbow Outlook Add-in as an End User

This guide explains how an end user can install the Rainbow Outlook Add-in.

Important: installation can be restricted by your Microsoft tenant policy. If your organization blocks custom add-ins, contact your Microsoft 365 administrator and use centralized deployment instead.

Prerequisites

• An active Microsoft 365 account.
• Access to Outlook on the web for custom add-in sideloading.
• The Rainbow add-in XML manifest file.

Step 1: Download the XML Manifest

Download the Rainbow Outlook add-in manifest file:

manifest-outlook-addin-prod-1.0.0.xml

If the XML opens directly in your browser, right-click and save the file locally.

Step 2: Install from Outlook Web

1. Open https://aka.ms/olksideload.
2. Sign in with your Microsoft 365 account.
3. Go to My add-ins.
4. At the bottom, select Add a custom add-in then From a file.
5. Select the downloaded XML manifest file.
6. Confirm the warning pop-up to complete installation.

Step 3: Final Check

• Restart Outlook Desktop after installation.
• Open an email and verify that Rainbow Telephony appears in More apps.
• You can pin the add-in so it appears automatically in future emails.