Granting write permission for calendar sharing with OWA 2010

The calendar sharing feature introduced in Outlook Web App 2010 (OWA) allows a user to grant access to their calendar to another user. To access the option, click on the Share option when in the Calendar and then on Share This Calendar. You’ll then be able to select the user(s) that you want to share your calendar with and define the level of information you want the recipient to be able to see in your calendar.

Internal support function returned an error sending to Distribution list

Issue:  Customer reported “Internal support function returned an error sending to Distribution list”
Resolution:
There is a duplicate, one-off contact in the DL, containing the Internet address for a member of the Microsoft Exchange Server Global Address List (GAL).
Do not use the identical display name for one-off contacts in a DL that also have Internet entries in the GAL.
Customer is advised to re-create the distribution list in Outlook