Sharing Calendars and other Mailbox Folders between Exchange 2010 and Exchange 2013.

Scenario:  You want to to access shared calendars/mailbox folders between a Exchange 2010 and Exchange 2013 mailbox. The clients used are either using Outlook 2013/2010 or OWA.

Resolution: When accessing a shared calendar/mailbox folder across the different Exchange platforms, follow these guidelines.


OWA:  By Microsofts design, a Exchange 2013 mailbox will not be able to open or edit the calendar entries of an Exchange 2010 mailbox. However, a Exchange 2010 mailbox will be able to access and edit a shared calendar of the Exchange 2013 mailbox.


For an Exchange 2013 mailbox accessing a shared calendar/mailbox folder of an Exchange 2010 mailbox

-Outlook 2013 is preferred.
-Make sure your Outlook version is patched to the latest update.  The Outlook version needs to be at least 15.0.4615.1000 or higher. To find the Outlook version number from within Outlook, click on File > Office Account > About Microsoft Outlook.  Its the Microsoft Outlook version and not the MSO version.
-If you are unable to locate the latest updates for Outlook, run the OffCat tool.  Click here for OffCat instructions.


For an Exchange 2010 mailbox accessing a shared calendar/mailbox folder of an Exchange 2013 mailbox

- If using Outlook 2010, make sure its at SP2 or higher.  If using Outlook 2013, make sure its at version 15.0.4615.1000 or higher.
- Your mail profile for Windows/Outlook needs to be forced to use Outlook Anywhere to reflect the architectural differences for Exchange 2013. Outlook Anywhere will allow Outlook to connect to the Exchange 2013 environment and access their mailboxes correctly. If not, you may not be able to connect to the 2013 mailbox OR your explicit permissions to the shared folder may not be honored. As an example, if you have editor permissions to the calendar of the 2013 mailbox, Outlook may tell you that you do not have permission and you need to request it.  Click here for steps to configure your mail profile to use Outlook Anywhere.