We all know that default apps are a common thing for users. This can be done via Intune for ages already. In the past it was done using a custom policy and a OMA-URI setting. This got much easier when Microsoft added the Default Associations Configuration to the Intune Settings Catalog.

In this blog I’ll show you how to configure the new Outlook app as your default Mail application. This will also configure the new Outlook app as the default mailto protocol application.

Note: This blog can also help you to configure the Default Associations Configuration for different apps. The examples in this blog are based on the new Outlook app.

Note: Keep in mind that there can only be 1 Default Association Configuration. If you already have one, you need to modify that policy in stead of adding a new one. In this case you will simply add the correct XML lines to your code and convert it to Base64 once again.

Export your required configuration using DISM

Note: This part should only be followed if you want to add more default applications to the Default Association Configuration or are not familiar with the process. If you do have a Default Association Configuration already, and still have the original XML file you can simply add some lines and convert it to Base64 again.

1: Pick a random device and configure the required default apps within the Settings menu.

2: Export your Default Association Configuration via DISM in the Command Prompt: DISM /Online /Export-DefaultAppAssociations:DefaultApps.xml

3: Open the XML file and clear all lines that should not be managed as a default file type/application. Once your XML is configured correctly you can copy all data to the clipboard.

4: Encode the XML file into Base64 format via https://www.base64encode.org/

Here is the XML input:

<?xml version="1.0" encoding="UTF-8"?>
  <Association Identifier="mailto" ProgId="AppXbx2ce4vcxjdhff3d1ms66qqzk12zn827" ApplicationName="Outlook (new)" />
  <Association Identifier=".eml" ProgId="AppXbx2ce4vcxjdhff3d1ms66qqzk12zn827" ApplicationName="Outlook (new)" />

Here is the Base64 output:


Create the Intune policy

Create the following policy:

  1. Navigate to https://intune.microsoft.com
  2. Go to Devices -> Configuration profiles
  3. Click Create -> New policy
  4. Platform: Windows 10 and later -> Profile type: Settings catalog -> Click Create
  5. Fill in a common name. For example: Windows – Default Association Configuration
  6. Click Next -> Click Add Settings
  7. Navigate to Application Defaults
  8. Select Default Associations Configuration and paste the Base64 output
  9. Scope tags are optional
  10. Assignment: Pick All Users or a specific user group. Make sure to test this first with a small amount of users.
  11. Finally, Create the policy.

Once the policy is deployed to your devices all .EML files will open with the Outlook (New) application. Also the mailto protocol will open the Outlook (New) application.

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