A shared mailbox makes it easy for a group of people to monitor and send email from a public email address, like info@contoso.com. When a person in the group replies to a message sent to the shared mailbox, the reply appears to come from the shared address, not from the individual person. You can also use the shared mailbox as a shared team calendar.
Tip: Before you can use a shared mailbox, the Microsoft 365 admin for your organization has to create it and add you as a member. For more information, ask your admin to see Create a shared mailbox, which describes what the admin needs to do.