You have an Exchange Server 2010 organization.You have a group named Group1 that contains 10，000 members.You need to ensure that an informative message is displayed when users add Group1 to the recipient list of an e-mail message. What should you do？（）

• A、Configure a MailTip.
• B、Create a transport rule.
• C、Create a Send connector.
• D、Configure an expansion server.