Exchange shared mailboxes provide basic functionality for help desk and customer service scenarios, but lack deeper features for many support situations.
How to configure Exchange mailbox permissions to remove auto-mapped mailboxes from a user’s Outlook profile.
When preserving Exchange Online mailbox data for departed users, is it better to use a shared mailbox or an inactive mailbox in Office 365?
How to manage shared mailbox sent items behaviour in Exchange Server 2013 and Office 365.
How to create shared mailboxes, and convert existing user mailboxes to shared mailboxes, in Exchange Online for Office 365.
The Office 365 public roadmap lists some good news for customers with changes to sent items behavior for shared mailboxes currently in development.