In Outlook 2013 and 2016, use the Sharing invitation to share calendar folders. Right click on the folder you want to share and choose Share > Share [folder name] to open the sharing invitation. Select the addresses from the Global Address List (GAL) and select the desired permissions. You can also share from Outlook on the web. When you use this method, permissions are set, but you can change the permissions as needed in folder permissions. Recipients will receive a sharing link that adds the calendar to their profile.

It's easy to share the default folders in your Microsoft Exchange mailbox: just give your co-worker permission to the folder. They can view the contents using the File, Open, Other users folder command. Sharing subfolders requires a bit more effort as the subfolders are not accessible from the Open Other Users Folder dialog.

Administrators can use the tools listed below to change the permissions on many mailboxes or folders at once.

For more information about Exchange server permissions, see Managing Exchange Server Permissions

In order to share Outlook subfolders with another user, you need to give them the desired permission (at least Reviewer) to the folder and at least Folder visible permission to every folder above the shared subfolder.

Right click on the shared folder and choose Properties. Go to the permission tab and assign permission to the person you want to share with.

Every folder in the path above this folder needs to have at least Folder visible permission, up through the top level, where Outlook Today is.

Sharing the folder

Before a person can view one of your folders, they need permission. If they are a Delegate to your mailbox (Tools, Options, Delegates) they may have permission to some or all of your mailbox folders. If so, the delegate just needs to open your mailbox as a secondary mailbox in their profile.

1. Right click on the folder you wish to share.
2. Choose Properties, select the Permissions tab.
   
3. If Default has Reviewer permission you won't need to add individual names to the list unless they need more permissions than the Default account has.
4. Click Add and select the names you want to share with from the Global Address List.
5. Give them at least Reviewer permission so they have Folder visible permission.
6. Click OK to close the dialog.

Repeat for each folder you wish to share.

If the person already has delegate access you won't need to do anything more. If they do not have any access to your mailbox, you need to give them Folder visible permission to the mailbox.

1. Right click on the mailbox root. This is the folder you click on to display Outlook Today.
2. The Default account typically has no permission to the entire mailbox. You can either give the Default account Folder visible permission or click Add and select your co-worker's name from the GAL.
3. Check the Folder visible box only. The permission level remains set to None.
4. Click Ok to exit the dialog.

Opening the shared folder

Once the folder permissions are set, the person who the folders are shared with needs to add the mailbox to their profile, as a secondary mailbox.

1. Go to Tools, Account Settings. (File, Account Settings in Outlook 2010 or 2013.)
2. Select your Exchange account and click Change (or double click)
3. Click More Settings
4. On the Advanced Tab, click Add
5. Type all or part of the name of the mailbox that was shared with you. Select the correct name if presented with a list of names.
6. Click Ok and work your way out of the dialogs and return to Outlook.

The mailbox you added is now in your folder list and the calendars you have permission to view will be listed in the Calendar pane. Any other folders that this user was given permissions to access will be visible in the folder list or appropriate modules.

View Shared Mailboxes in Outlook Mac

If the user has full access rights, go to Tools, Accounts and Add the account as another email account. Enter the email address of the shared mailbox. On the authentication screen, choose Sign in with another account and enter your credentials. Complete the Add account wizard.

For users with delegated permissions, open it from Tools, Accounts > Advanced > Delegates. Add the mailbox under Open these additional mailboxes

Video Tutorial: Configure Permissions to Share Subfolders

The first part of the video shows how to set the permissions on the mailbox in Outlook 2010. The method is the same in all versions, however, the Account Settings dialog is on the Tools menu in Outlook 2007 and older and the account dialogs vary.

A video tutorial recorded in Outlook 2007 on Windows XP is here: Share Exchange Mailbox subfolders in Outlook 2007

The View in Outlook

This screenshot is from the folder above the shared subfolder. It has Folder Visible
permission. This is what the folder owner sees >

With folder visible permission, the user can see the folders in the folder path but they cannot see the contents of the folders.

This is what the person with Folder Visible permission sees when they open the shared folder to their profile. As you can see, they can see the folder but not the folder contents. >