Customizing Search Result Display for .eml files at Site Collection level

Hi everyone,

I’ve noticed a specific behavior regarding how SharePoint handles search results for .eml files and I am looking for a way to optimize this.

Observation: Following a migration of emails into a SharePoint Site Collection, the search results currently display the Filename as the primary heading. Since these filenames are GUIDs, they provide no context to the users. The Title property (which contains the actual email subject) is available but is not being used as the main display value in the search results.

Goal: The objective is to change the search result display so that the Title/Subject is shown instead of the Filename, making the results meaningful for the end-users.

Current Constraints:

• Permissions: Access is limited to Site Collection Administrator (no Tenant Admin access).
• Environment: Must remain Out-Of-The-Box. PnP Modern Search or other third-party web parts cannot be deployed in this environment.
• Scope: Changes need to be implemented at the Site Collection level, as tenant-wide search schema modifications are currently not an option.

Technical Question: Is there a way to influence the result display logic or the mapping of Managed Properties specifically within the Site Search Schema to achieve this? I am looking for guidance on whether this can be solved through site-level configuration or if there are other OOTB workarounds to prioritize the Title property in the search UI.

Any insights or documentation on how to approach this at the site level would be greatly appreciated.