In Fedora 42 I added all account I needed, IMAP, Gmail, MicrosoftO365 etc.
After the update to Fedora 43 (via USB) I lost only the Microsoft mails, so I tried to added them from the settings but I have this error message, do you know why ? (if you need I can translate it)
What you’re showing there in the screenshot is an IMAP type of setup, which wouldn’t work with a Microsoft account.
However, Microsoft 365 can be set up correctly in Settings → GNOME Online Accounts (GOA), and, as you’ve mentioned, it used to work with Geary. With recent versions of Geary this seems to be an issue though, it doesn’t pick up Microsoft 365 accounts. This is an already reported issue against Geary, you can follow the bug report here: