1. Sign in with a global admin account or Exchange admin account. If you get the message "You don't have permission to access this page or perform this action," then you aren't an admin.
2. In the admin center, go to the Teams & Groups > Shared mailboxes page.
3. On the Shared mailboxes page, select + Add a shared mailbox. Enter a name for the shared mailbox. This chooses the email address, but you can edit it if needed.
4. Select Save changes. It may take a few minutes before you can add members.
5. Under Next steps, select Add members to this mailbox. Members are the people who will be able to view the incoming mail to this shared mailbox, and the outgoing replies.
6. Select the +Add members button. Put a check mark next to the people who you want to use this shared mailbox, and then select Save.
7. Select Close.
You have a shared mailbox and it includes a shared calendar. Go on to the next step: Block sign-in for the shared mailbox account.
