Hi @giobaxx
Are you using Exchange Online (Microsoft 365) as email service?
If yes, it is not possible to access shared mailbox with IMAP in Outlook.
As basic authentication is blocked in Exchange Online and Outlook doesn't support OAuth for IMAP.
For more details please refer to this link: Deprecation of Basic authentication in Exchange Online
If it is possible, you can use MAPI/HTTP instead as a workaround.
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