SMUS Shared Mailboxes
In Office 365, access to Shared Mailboxes is now different. There are three different methods for accessing your shared mailbox, outlined below:
Outlook Web Access, full method
If you normally check your personal email using Outlook Web Access and want to send and reply to emails as the shared mailbox address, you should follow this method.
Outlook Web Access, quick method
If you normally check your personal email using Outlook Web Access and want to check emails (but not reply to them) as the shared mailbox, you should follow this method.
Outlook 2013
If you normally check your email using Outlook 2013, follow this method to add the shared mailbox.