Hi @Martin Fessler ,
Welcome to our forum and post here.
Having your mailbox data in the Microsoft Cloud lets you use the new features of the Outlook client (New Outlook for Windows, Outlook for iOS, Outlook for Android, Outlook.com, or Outlook for Mac) with your non-Microsoft account, just like with your Microsoft accounts.
The following article explains the functions that can be experienced after synchronizing to Microsoft Cloud:
Sync basics - what you can and cannot sync
What happens when I sync my account to the Microsoft Cloud?
If you want to configure your account without synchronization to Microsoft Cloud, you can click on the Not [Google, iCloud, Yahoo, etc.]? link at the top right of the window. Turn off Sync with Microsoft Cloud by clicking on the toggle, select your desired email provider, and click Continue. More information, see: Add an account without using Microsoft Cloud
Many features of our current products are designed and upgraded based on customers’ feedback. With requirements like this increase, the problem may well be released in the future, you can make a suggestion via this link.
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