outlook with windows

Question

how to revert back to old outlook.

as I cant send documents from the window.

Answer 1

Hi,
The toggle should be there on the top right to switch back.

If the toggle isn't there, do this:

In the Windows search, 

Type cmd, right-click it, and choose Run as Administrator.

Execute this command:

reg add "HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Preferences" /v UseNewOutlook /t REG_DWORD /d 0 /f

I’m eager to hear back and work together to find a solution.

Answer 2

To go back to classic (old) Outlook and fix sending documents from Windows apps, use these steps:

1. Switch from new Outlook to classic Outlook
   • Open the new Outlook for Windows.
   • At the top-right of the Outlook window, locate the toggle.
   • Click the toggle and choose Switch back to classic Outlook.
     • This toggles you back so that the next time Outlook starts, it opens classic Outlook.
   • If you only need classic Outlook temporarily, choose Use classic Outlook this time instead.
   If the toggle does not appear:
   1. Open Start → search for Registry Editor → open it.
   2. Go to: Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Preferences
   3. Double‑click UseNewOutlook.
   4. Set Value data to 0 and save.
   5. From the Start menu, launch Outlook (classic) (the Outlook icon without the New tag).
2. Make sure classic Outlook is installed
   • If classic Outlook is not installed, the toggle will not show.
   • In that case, follow the guidance in “You can't open classic Outlook on a new Windows PC” (linked from the articles below) to install or reinstall classic Outlook, then repeat step 1.
3. Fix “can’t send documents from Windows/Office apps”
   • New Outlook is not MAPI‑compliant, so sending directly from Word/Excel/PowerPoint or some Windows “Share” actions fails with errors like “MAPI failure” or “Unable to share”.
   • After switching back to classic Outlook and ensuring it is the default mail client, sending documents from Office apps should work again.

If documents still do not send after switching back, confirm that classic Outlook is set as the default email app in Windows Settings and that it opens when choosing “Send as attachment” from Word/Excel/PowerPoint.

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References:

• Toggle out of the new Outlook for Windows
• Go back to classic Outlook button not working correctly in new Outlook
• Troubleshoot attachment problems in Outlook for Windows
• I am unable to share my file either as a presentation or document type or pdf type by none of the microsoft office apps (Word, Excel, Powerpoint). It is continuously showing "Mapi Failure" and "Unable to Share" errors. What can I do? - Microsoft Q&A