The usage of “real” shared mailbox (without password so without a real microsoft user behind) is really nice when you need team emails…
Unfortuntly, it is not possible to connect a shared mailbox (without password) as personal email in Hubspot.
Reason (given by support):
The IMAP/SMTP workaround might have worked in the past, but is no longer viable since Microsoft deprecated support for basic authentication for O365 some time last year. For context, basic authentication is when you log in with an email/username and a password, whereas modern authentication is done through Oauth (this is where you sign into the Microsoft page to connect).
It will be really appreciate to be able to connect this kind of mailboxes.