Exchange 2010 Shared Mailbox Calendar "Share Calendar" Option Greyed Out

By default, when viewing a Shared Mailbox Calendar in Outlook, the Share Calendar option is greyed out/unavailable. This is by design because users aren't really supposed to share calendars that are already shared. But on occasion, there might be a business need for a user to share that calendar with others.
The workaround is to use OWA to share it out.

There are two ways to go about sharing, and both require Full Access on the Shared Mailbox.

The first option is to open OWA with the shared mailbox address at the end like so:

www.webmail.exchangeitup.com/owa/sharedmailboxcalendar@exchangitup.com

**Note** Change the domain and Shared Mailbox name to match your environment

1. Once you've got the mailbox open, hit Calendar in the lower left pane.

2. With the calendar open, click Share on the top ribbon, then click Share This Calendar in the drop-down.

 

 

 

3. In the new window, pick your contacts you want to share with, set a subject, and pick the Free/Busy options.

4. Send it away.

The second option is to log into OWA as you normally would, and in the upper right corner, click your Name.

In the Select Mailbox field, type the Shared Mailbox name, and hit Open.

Then follow steps 1-4 above.