It is great that single tenant support is on its way in version 4.1. I think one more way to improve usability of the Microsoft 365 channels is to make the api endpoint + scopes configurable so that both graph- and outlook apis can be used.
Endpoint and scopes that are beeing used today in zammad are hard coded to the outlook api:
https://outlook.office.com/IMAP.AccessAsUser.All https://outlook.office.com/SMTP.Send offline_access openid profile email
However some users may be required to connect via the graph api instead, according to
And the endpoint would be:
https://graph.microsoft.com/ + tenant id or common
Probably isnt much code needed for this feature since (according to the link above): “Microsoft Graph v1.0 matches Outlook v2.0”