Open Another Mailbox in Outlook

Most shared mailboxes are delegated which means they will be pushed to your Outlook client automatically. However, sometimes you need to manually add a mailbox. To do so, please follow this guide:

For the desktop Outlook client

With Outlook open, click the File tab.
Under Account Information, click Add Account
Enter the email address of the mailbox and click Connect
If prompted for the mailbox type, select 365
Enter the password for the mailbox, if prompted
If prompted to sign in to this app or all apps, select just this app
Click Finish

Your mailbox should appear in the list on the left-hand side.

To open another mailbox in Outlook on the Web (browser)

The method depends on whether the mailbox has had permissions delegated to you (part 1) or a standalone mailbox you know the credentials to access it (part 2)

If you're not sure which to use, speak to IT Support

Part 1 - delegated mailbox

Click on your name/portrait in the top right corner
Click Open another mailbox
Enter the name or email address of the mailbox you want to open

Note: you should not be prompted for the password if you have delegated permissions

Part 2 - standalone mailbox

Click on your name/portrait in the top right corner
Click sign in with a different account
Select Use another account (if it appears)
Enter the email address of the account you want to login as
Enter the password for the account