I have a user that would like to share his calendar (limited details) with another user outside our organization. Our email is hosted by Microsoft (Office 365) and I believe the other user's email is hosted by an in house exchange server. When my user tries to share his calendar he gets the following message: Calendar sharing is not available with the following entries because of permission settings on your network: John Doe<email@example.com> - Problem: This recipient's organization is not set up for secure sharing.
The above recipients can view your calendar if you publish. Would you like to publish your calendar? (we answered "No")
Any help is appreciated in resolving this issue. Thank you.