Hi, I'm having problems with sharing my whole calendar with my co-workers. I have been able to send appt and meetings through the calendar without any problems. When I try to share the whole calendar, it has an error while preparing to send sharing message?

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 Web App to share the calendar or to set up calendar permissions. For more information about how to do this, see the following Microsoft resources:
  • How do I share my calendar?       (http://office.microsoft.com/en-us/web-apps-help/sharing-your-calendar-HA103842904.aspx#_Toc342645965)   
  • Video: Share your Office 365 calendar       (http://office.microsoft.com/en-us/office365-suite-help/video-share-your-office-365-calendar-VA103991824.aspx?CTT=1)   
  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:
  • Outlook 2013: Video: Share your calendar       (http://office.microsoft.com/en-us/outlook-help/video-share-your-calendar-VA103988996.aspx?CTT=1)   
  • Outlook 2010: Video: Share your Office 365 calendar       (http://office.microsoft.com/en-us/outlook-help/share-or-publish-your-calendar-1-05-RZ103433663.aspx?CTT=1&section=2)   
  After the calendar sharing request is sent or the calendar permissions are set up through Outlook 2010, Outlook 2013, or Outlook Web App, users who are using Outlook 2007 will be able to see those changes in their Outlook profiles.

Source link: http://support.microsoft.com/kb/2836889/en-us

Tony Chen
TechNet Community Support