Can't open Outlook email messages stored in folders on laptop

The behavior most likely comes from the recent Outlook changes and which Outlook edition is being used to open saved message files.

Key points and actions:

1. Confirm the file type
   • Messages saved from classic Outlook are usually .msg files.
   • New Outlook for Windows has limited support for opening local .msg files; classic Outlook for Windows handles them best.
2. Open the files with classic Outlook for Windows
   • Make sure classic Outlook (the full desktop Outlook for Microsoft 365) is installed and activated on the same Microsoft 365 account.
   • In File Explorer, right‑click one of the saved email files → Open with → choose Outlook (classic desktop icon, not “new Outlook” or a browser).
   • If prompted to choose a default app, select classic Outlook and set it as default for .msg files.
3. If classic Outlook is already in use but the files still will not open
   • Check whether this matches the known issue “Error when opening a saved .MSG file twice in classic Outlook.” In that case, the error text is:

     “We can’t open ‘email.msg’. It’s possible the file is already open, or you don’t have permission to open it.”

   • If that is the error, install the fixed Outlook build:
     1. In classic Outlook, go to File → Office Account → Update Options → Update Now.
     2. Ensure Outlook is updated to Version 2507 Build 19029.20156 or later (or one of the backported fixed builds listed in the reference).
   • As a temporary workaround for that specific bug, open any other email in Outlook (for example, from Inbox) and then reopen the .msg file.
4. If Outlook Desktop itself will not open or keeps crashing
   • Fully uninstall Microsoft 365 Apps (Office) from Windows.
   • Reinstall Microsoft 365 from the subscription portal, then sign in with the same Microsoft 365 account and retry opening the saved messages.
5. If none of the above works
   • Use Outlook on the web (OWA) or new Outlook for Windows for current mail, and keep classic Outlook installed specifically for opening the local .msg files until Microsoft provides broader support in new Outlook.

References:

• Error when opening a saved .MSG file twice in classic Outlook
• What to do when Outlook will not open on my PC? - Microsoft Q&A