This article explains how to back up or copy individual messages in Windows Mail. It includes information on how to open or restore the backup copies.
How to Back Up Your Emails in Outlook | Microsoft Outlook Tutorial | Microsoft 365
You may have emails in Windows Mail that are of particular importance. You can back up all of your email data, and you can create backup copies of individual messages by exporting the emails as .eml files.
Back up or copy individual messages in Windows Mail by exporting the messages as EML files:
Open the folder containing the message you want to back up or copy.
