How to Access A Shared Mailbox, Office 365 Group Mailbox, or User Mailbox

You can access a Shared Mailbox, Office 365 Group Mailbox, or User Mailbox if you have been granted the appropriate permissions to the specified mailbox.

Instructions (Outlook on the Web)

Sign in to your account in Outlook Web App.
On the Outlook Web App navigation bar, select your name. A list appears.
Select Open another mailbox.
Type the email address of the other mailbox that you want to open and then select Open. Or, start typing and then select Search contacts and directory to find the mailbox you want to open. Select the shared mailbox you want to open, and then select Open. Another Outlook Web App session opens in a separate window, allowing access to the other mailbox.

Instructions (Outlook for Mac)

Open Outlook on your Mac
On the File menu, click Open > Shared Mailbox.
Enter the mailbox name or email address and click Add.

If the mailbox was just created, it can take up to 48 hours for the mailbox to show up in the Global Address Book (which is needed for step 3).

Instructions (Outlook for Windows)

Open Outlook on your PC
Click on the File tab
Click on Open & Expert
Click Other User's Folder
In the Name box, enter the name of Mailbox of which you have been granted Sharing or Delegate Access permissions, or click Name to select from a list.
Select the Folder Type you wish to open.
Click OK