Many Office 365 customers I talk to are concerned about how to audit changes to their organization’s mailboxes within Exchange Online. How do I track changes to the administrator roles in my tenant? How do I know if someone’s mailbox has been accessed by another person? How do I verify Litigation Hold is working? Read on and all shall become clear.
http://www.knowledge-vault.com/blog/office365/mailbox-auditing-for-office-365-part-1.html