Hello, Wolfram
Welcome to Microsoft Community.
I realize that you have encountered a problem that when you open the Excel file which is an attachment in an email in Outlook, the auto-save feature for it doesn't work. I understand how you feel.
I think your guess is very reasonable. The Excel file in the email might indeed be stored in some temporary Outlook folder. Even though it says “Auto Save Enabled”, the file will probably be automatically saved to this temporary folder on “Your iPad”.
When you open the Excel file from email next time, you can try to manually save it to OneDrive.
- Click on the three dots in the top-right corner and select “Upload File” or “Save a Copy” to save the file to OneDrive.
- Then see if the file appears in “Recent” and whether the auto-save function works when you edit the Excel file saved in OneDrive.
Please understand that our initial response may not always solve the problem immediately. Feel free to post back if you need further assistance.
Best wishes,
Lucia Wu - MSFT | Microsoft Community Support Specialist