How to open another mailbox in Office 365

  • June 30, 2021 at 10:14 AM #1301
    Chris Mathews

    Did you know that you can open a delegated or shared mailbox in Office365 using a browser? It is fairly simple and should take you no time at all.

    1. First, open a browser (Chrome, Firefox, Edge, or even Internet Explorer)
    2. Go to
    3. Sign in with your username and password
    4. Left-click on the icon (might be your initials or a picture of you set one)
    5. Select “Open another mailbox”
    6. Enter the mailbox you wish to open
      • If you are delegated to the mailbox it will open, if not, you will get an error.
      • If you get an error, contact your IT department for more information.
        • If you were just added to the mailbox as a delegate, it can take up to sixty (60) minutes for the permissions to take effect

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