When you use Microsoft Office Outlook 2007 to share your calendar, you receive the following error message:
Error while preparing to send sharing message.
You receive this error message only when you use Outlook 2007 and connect to a Microsoft Exchange Server 2013 mailbox or a Microsoft Exchange Online mailbox.
Also, if you try to check the permissions on the calendar, you may receive the following error message:
An error occurred when setting schedule permissions.
This issue occurs because of a limitation in how Exchange Server 2013 and Exchange Online set Free/Busy permissions.
To work around this issue, do one of the following:
Use Outlook on the web (formerly known as Outlook Web App [OWA]) to share the calendar or to set up calendar permissions. For more information about how to do this, see the following Microsoft resources:
Users who are running Microsoft Outlook 2013, Outlook 2010, or Outlook 2007 can directly accept sharing requests and invitations that are sent from Outlook Web App.
Use a computer that has Outlook 2013 or Outlook 2010 installed to create a temporary Outlook profile. After the profile is set up, you can use Outlook 2013 or Outlook 2010 to send calendar sharing requests and to edit calendar permissions.
For more information, go to the following Microsoft websites:
After the calendar sharing request is sent or the calendar permissions are set up through Outlook 2010, Outlook 2013, or Outlook on the web, users who are using Outlook 2007 will be able to see those changes in their Outlook profiles.