Error while preparing to send sharing message – error sharing calendar in Outlook 2007 connected to Office365

Since I have switched from MS Exchange 2007 running on SBS 2008 to hosted Exchange – Office 365 few bugs shows up here and there. Here is the first one. Since not every user is running on the latest Microsoft Office 2013 product and some of them are still using MS Outlook 2007 they are running to few issues while trying to share for example their calendars with other users in the office.

Everything looks fine and works to the point when you press SEND to share calendar with others – error message pops up on your screen:

Error while preparing to send sharing message

You have no other explanations or options except to click OK to close the message but your calendar is not being shared. After few minutes of research, I have discovered Microsoft KB that covers this problem between MS Outlook 2007 and MS Exchange 2013 – Office 365.This issue occurs because of a limitation in how Microsoft Exchange Server 2013 and Exchange Online set Free/Busy permissions.


  • Log on to and share the calendar from the Web App
  • Install MS Outlook 2010 or Outlook 2013 as they are not experiencing this issue while connected to Microsoft Exchange Server 2013

MS KB2836889 – for more details check this MS KB article.


Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.