How to Sideload an Outlook Mobile Add-In on a Managed iOS Device

If you manage iOS devices through an MDM solution like Microsoft Intune or Jamf, you may need to deploy an internal or custom Outlook Mobile add-in without publishing it to the public Office Store. Standard add-in deployment through the Microsoft 365 admin center does not push add-ins to the Outlook mobile app on iOS. This article explains how to sideload an Outlook Mobile add-in on a managed iOS device using an XML manifest file and an MDM policy. You will learn the exact steps to prepare the manifest, configure the MDM profile, and verify the add-in appears in Outlook.

What Sideloading Means for Outlook Mobile Add-Ins

Sideloading an add-in means installing it directly from a manifest file rather than through the public Office Store or the Microsoft 365 admin center. For Outlook Mobile on iOS, the add-in manifest must be delivered as part of an MDM configuration profile. The MDM pushes the manifest to the device, and Outlook reads it on launch. The add-in then appears in the compose or read ribbon depending on the extension point defined in the manifest.

Before you begin, you need three things:

• An add-in manifest XML file that targets mobile form factors.
• An MDM that supports custom configuration payloads for iOS. Microsoft Intune is the most common option.
• Outlook for iOS version 4.21 or newer installed on the managed device.

Steps to Prepare and Deploy the Add-In Manifest

1. Create or update the add-in manifest
   Open your existing add-in manifest XML file. Add a element with the xmlns attribute set to http://schemas.microsoft.com/office/mailappversionoverrides/1.1. Inside it, add a child element with xmlns set to http://schemas.microsoft.com/office/mailappversionoverrides/1.1/mobile. Define a element that contains . Inside the host, add a block for desktop and a separate block for iOS and Android. The MobileFormFactor block must include the and elements that match your add-in logic. Save the file with a .xml extension.
2. Validate the manifest
   Go to the Microsoft 365 admin center and navigate to Settings > Integrated apps. Select Add-ins and click Upload custom add-in. Upload your manifest file. The validation tool checks the schema and reports errors. Fix any issues before proceeding. Remove the uploaded add-in after validation — you will not deploy it through the admin center for mobile devices.
3. Sign in to Microsoft Intune
   Open the Intune admin center at https://intune.microsoft.com. Go to Devices > Configuration profiles. Click Create profile. For Platform, select iOS/iPadOS. For Profile type, select Templates and then Custom. Click Create.
4. Configure the custom profile payload
   In the Basics tab, enter a name like Outlook Mobile Add-In Sideload. In the Configuration settings tab, click Add. For Name, enter OutlookAddInManifest. For Description, enter the add-in name. For Payload URL, leave it blank unless your manifest is hosted on a secure HTTPS server. For the actual manifest content, you must base64-encode the XML file. Use a tool like the macOS terminal command base64 -i manifest.xml or an online encoder. Copy the base64 string and paste it into the Payload field. For Identifier, enter com.microsoft.outlook.mobileaddins. Click OK.
5. Assign the profile to a device group
   In the Assignments tab, select Include groups and choose the Azure AD group that contains the managed iOS devices. Click Next, review the settings, and click Create. Intune pushes the profile to the devices within the next sync cycle.
6. Verify the add-in on the iOS device
   On a managed iPhone or iPad, open Outlook for iOS. Tap the plus icon (+) in a new message or a reply to open the add-in ribbon. The sideloaded add-in appears as an icon. Tap it to test its functionality. If the add-in does not appear, check that the device received the profile by going to Settings > General > VPN & Device Management. Tap the management profile and confirm the Outlook Add-In payload is listed. Also confirm Outlook for iOS is version 4.21 or later under Settings > About.

Common Sideloading Failures and How to Fix Them

Add-In Does Not Appear in the Ribbon

The most frequent cause is an incorrect manifest schema. Verify that the element exists and that the uses a supported value such as MessageReadCommandSurface or MessageComposeCommandSurface. Also confirm the base64-encoded string in the Intune payload is complete and does not contain line breaks. Outlook ignores malformed payloads silently.

Profile Shows as Not Compliant in Intune

This usually means the device has not synced with Intune. Ask the user to open the Company Portal app and tap Check Status. If the device is supervised, the profile pushes automatically. On an unsupervised device, the user must manually accept the profile in Settings > General > VPN & Device Management.

Add-In Works on Desktop but Not on iOS

The manifest may define extension points only for DesktopFormFactor. Add a separate MobileFormFactor block with the same function file and extension points. The mobile add-in cannot use the same JavaScript file if it references desktop-specific APIs like Office.context.mailbox.item.getRegExMatches. Create a mobile-specific function file that uses only the APIs listed in the Outlook mobile add-in documentation.

MDM Custom Profile vs Centralized Deployment: Key Differences

Item	MDM Custom Profile (Sideload)	Centralized Deployment (Admin Center)
Deployment method	Configuration payload pushed via Intune or Jamf	XML manifest uploaded to Microsoft 365 admin center
Supported Outlook clients	Outlook for iOS only (Android requires separate payload)	Outlook on Windows, Mac, and web
Manifest source	Base64-encoded XML stored in the profile payload	Direct URL to a hosted manifest or uploaded file
Update process	Replace the profile payload with a new base64 string	Update the manifest in the admin center or republish the app
User acceptance	Required on unsupervised devices	No user action needed

This article walked you through creating a mobile-compatible manifest, encoding it, and deploying it through Intune as a custom configuration profile. You can now sideload internal Outlook add-ins to managed iOS devices without publishing to the Office Store. As a next step, test the same manifest on Android by creating a separate Intune profile with the identifier com.microsoft.office.outlook.mobileaddins. For advanced scenarios, use the Office Add-ins diagnostic tool in Outlook for iOS to capture logs when the add-in fails to load.