ITSM 17.x and MS Office 365 with shared mailbox.
No. Microsoft Office 365 Shared mailboxes are not supported.
The Shared mailboxes will not work with the Java maileater shipped in 17.x. This has not been tested or certified.
We cannot give a guarantee as whether this would work as the Shared mailbox doesn't have a username and password. It also requires the Javamail property (Our new Java Maileater uses javamail internally) to have NTLM and plain authentication to be disabled in code while connecting to server.