You have an Exchange Server 2010 organization.  All users access their mailboxes by using Outlook Web App （OWA）.  You need to plan a solution to reduce the number of e-mail messages that are accidentally sent to distribution groups that contain company executives.  What should you include in the plan？（）

• A、custom MailTips
• B、dynamic distribution groups
• C、Outlook Protection Rules
• D、sharing policies