Who is this article for?

Administrators who want to fix File system AutoDiscovery not working in 2026.

Some admin permissions might be required.

This article explains how to resolve a known issue in Mail Manager version 15.1 where File system AutoDiscovery stops working for some collections.

1. Understanding the issue

In Mail Manager version 15.1, File system AutoDiscovery may stop working for some collections (though not all). This issue does not affect SharePoint AutoDiscovery.

The problem occurs because the default AutoDiscovery File system update rule was accidentally set to 4 instead of 1. This means that if more than 100 locations have changed in a collection, AutoDiscovery will not run.

2. Checking if AutoDiscovery is working

To verify whether AutoDiscovery is functioning correctly, follow these steps:

1. Go to Mail Manager.
2. Select Tools.
3. Choose Locations.
4. Check the timestamp for the last discovered time.

If AutoDiscovery is working correctly, the last discovered time should be within the hour.

Note: The AutoDiscovery testing tool will run successfully even when this issue occurs.

3. Resolving the issue

To fix the AutoDiscovery issue, follow these steps:

1. Go to the Mail Manager shared config folder.
2. Right-click on the AminEmailFiling.cfg file.
3. Select Open with and choose a plain text editor, such as Notepad.
4. Add this text on a new line: #*FileSystemAutoDiscoveryLocationsUpdateRule=1
5. Find the line that begins with AdminUpdateDateTime.
6. Increment the value on that line by 1 to ensure users pick up the changed file.
7. Save the file.

4. Applying the changes

To apply the configuration changes, follow these steps:

1. Close Outlook.
2. Reopen Outlook.

A new discovery will start running in the background with the new settings. Alternatively, users can wait and the changes will be picked up automatically in due course.