Hi,@Roger Roger
Thanks for posting your question in the Microsoft Q&A forum.
According to your description, I understand that one of your Mac users is getting an error when sharing the calendar.
I need some information below to narrow down the issue:
1. Are other Mac users experiencing the same problem?
- Try logging into Outlook on Windows to see if the same problem still occurs.
- I suspect that calendarshare@contoso.onmicrosoft.com is the DL address that the user try to share. Please help confirm this with the end user.
Here is my advice based on my experience:
According to my tests, users can only create private calendars in Other Calendars in Outlook for Mac.
It is possible to share the calendar to other people (mailbox).
It is not feasible to share the calendar to the DG (Distribution Group), but we can share the calendar to the SG (Security Group). So we suspect that the error occurred because the user shared the calendar to a DL, please share the calendar with other users to see if the same problem occurs.
If my answer is helpful to you, please mark it as the answer so that other users can refer to it. Thank you for your support and understanding.