If your mailboxes are hosted by Microsoft 365 and you want to access them using Zammad, it’s possible using IMAP/SMTP as the data transferring protocols and OAuth as the protocol to authenticate against the M365 servers. (Documentation)
In the next release, the additional possibility will be added to use Microsofts GraphAPI as the transferring protocol. For reference: Feature Request & Issue.
I am curious, are there good arguments to keep the support for IMAP/SMTP in the context of Microsoft 365 mailboxes on the long run? Other than “having options”? If you are an admin that wants/needs to stick with IMAP/SMTP in this scenario, please share your reasons.