To access another mailbox from within your own mailbox in Office 365 Outlook Web, follow the steps below. It’s worth noting that this will only work if an admin has given you the relevant permissions to the mailbox you’re trying to open. Once the permissions are added, it can take up to 2 hours to become effective in Office 365, however is usually much sooner.

The following article is available as a downloadable PDF for easy distribution to your users. More End User How To articles are available to view online and download here, with more being added regularly.

Office 365 – Outlook Web Access

1. Login to Office 365 Outlook using your own email address and password.
2. Click on your display photo / initials in the upper-right corner of the window and click “Open another mailbox” as shown in the screenshot below:
   
3. The “Open another mailbox” prompt will now appear. Type the email address of the mailbox you want to view in here and click “Open” as shown below:
   
   Depending on your browser, the mailbox will now open in a new tab/window.

Office 2016, Office 2019 and Office 365 – Locally Installed Outlook

If you have access to another mailbox, this should automatically appear beneath your own mailbox folders in the “Folder Pane” as show below.

Be aware that if this is your first time signing into Outlook on your computer, it may take some time for the mailbox to appear,

As mentioned above, this article is available as a downloadable PDF for easy distribution to your users. More End User How To articles are available to view online and download here, with more being added regularly.