All larger email providers are slowly but steadily moving away from regular password-based authentication for email protocols like IMAP and SMTP. There are multiple options to do so. For example, iCloud requires you to generate application passwords for IMAP. Gmail is pushing OAuth2, even though it also allows application passwords.
EmailEngine is capable of using MS365 shared mailboxes via OAuth2. This involves adding the shared mailbox to EmailEngine, while the OAuth2 authentication process is handled by a user who already has access to the mentioned mailbox. However, there is a disadvantage to this. At present, EmailEngine anticipates that each OAuth2