Don’t use “Outlook (new)” in #Windows 11. I just did a tcpdump and looked also at my #mail servers when setting up an account in there. The mail client only spoke with Microsoft-servers, never with my mail-servers and I saw on my mail-servers only connections from Microsoft-IPs.
Microsoft lays hands on login data: Beware of the new Outlook

The free new Outlook replaces Mail in Windows, and later also the classic Outlook. It sends secret credentials to Microsoft servers.

heise online

@nielsk I noped out of there as soon as I saw the notification that they would be syncing my data to their ~cloud~

I didn't even realize it included passwords too. That's even worse than I thought.