Create Shared Mailboxes in Office 365
You can now create Shared Mailboxes directly from the Web Based Administration Console, including setting and modifying Access Permissions and Send As rights.
To create a new Shared Mailbox:
Log in to the new portal and click Exchange from the Administration Menu.
Click the Shared Mailbox section at the top then click the Plus sign to add a new Shared Mailbox.
You will now be presented with the new Shared Mailbox dialog box. Here you can choose the name, email address and who has access or send as permissions for this mailbox.
You can also edit an existing shared mailbox by selecting it and clicking the pencil icon. You can now edit all of it’s properties, including permissions and email addresses.