Outlook Web Access - How to open different mailbox (shared, other person, ...)

When logged on to Outlook Web Access (outlook.com)

Click your profilepicture at the top right and choose "Open another mailbox"

In the pop-up window, enter the name of the person/mailbox you want to open

When you have selected the correct mailbox, click Open

Your chosen mailbox will open up in a new tab in your web browser