Hi @Marc ALLAVENA ,
Most other account types, such as IMAP accounts, Microsoft 365 accounts, Exchange accounts, and Outlook.com accounts use an Offline Outlook Data File (.ost) file to store a synchronized copy of your mailbox information on your local computer.

Based on my research, the corrupted date file may cause the problem.
So, we recommend that you rebuild the OST file. That is, delete the OST file, and then let Outlook create a new OST file and download the information again from Exchange Server.
To delete the old Offline Outlook Data Files (.ost), go to drive:\Users\user\AppData\Local\Microsoft\Outlook.
The next time you configure your account, a new local copy is generated by connecting to the server, so you don't have to worry about losing files.
Then create a new profile from control panel: Go to Control Panel > Mail > Show Profiles > Add, re-add your account and see if you can resynchronize the folder.
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