Open an Outlook Shared Mailbox

If you have permission to use a shared mailbox, you can access it using the Outlook desktop client or using Office 365 in the web browser. Instructions for the various current versions of Outlook are available below:

Outlook (Microsoft 365 version) for Windows

Outlook Microsoft 365 for Mac (New Experience)

  1. Click Microsoft Outlook in the upper left and click Preferences
  2. Select Accounts and then click Delegation and Sharing underneath your account details
  3. Click the Shared With Me tab to the right, and then click the plus + button to add the Shared Mailbox you've been granted access to by searching for it in the provided window. Click the mailbox name to add it, and then click Done
  4. The Shared Mailbox will appear below your account on the left-hand pane, in addition to it's Calendar in the Calendar area. 

Outlook (Office 2016) for Mac

  1. Go to Tools on the menu bar and select Accounts…
  2. Click the ‘+’ in the lower left corner and select New Account… to add a new account.
  3. Add your group mailbox email address and click Continue
  4. Click Sign in with another account and then enter your universal cloud username (in the form of and password.
  5. Click Done
  6. You can change the Account description to the mailbox name. Close out of this window; the group mailbox will now be listed!

Access a shared mailbox using a Web browser:

  1. Login to OWA as yourself.
  2. Select your name in the upper right corner
  3. Click the link to Open another mailbox...
  4. Search for the mailbox you wish to open
  5. Click Open when the mailbox is found.

Mobile Devices

The Outlook app for iOS and Android allows you to add a shared mailbox from the settings. 

If you are not able to access a shared mailbox in the Outlook client:

First try to open the mailbox using a Web browser as described below. If you can access the mailbox using a Web browser, try removing the mailbox and re-adding it to Outlook. If it was recently created, there may be a delay between when the inbox is created and when it's in a fully usable state. If you're not sure if you have permissions to a shared mailbox, simply email the ATUS Help Desk to verify that you have access to that mailbox.

If the mailbox will not open for you, contact the Help Desk for assistance.