You work as the enterprise exchange administrator at Xxx .Xxx is using Microsoft Exchange Server 2010 as their messaging solution.The Xxx employees at Xxx use Outlook Web App to access their mailboxes.You receive a complaint from a Xxx employee named Mia Hamm that her mailbox is unavailable.What actions must you take to resolve this problem？（）
- AYou must change the WEB Outlook Provider.
- BYou must change Mia Hamm’s mailbox features.
- CYou must change the EXPR Outlook Provider.
- DYou must change the DNS forwarding.