You recently took over as the Exchange 2010 Server Administrator for Xxx .The previous administrator allowed users to pick the email addresses of their choice.This caused much confusion， as each user wanted a different email address.You want to standardize the emails addressed across the entire organization.You have determined that the naming convention will be the first letter in their first name and then their last name.For example， the e-mail address for John Smith would be jsmith@Xxx .What should you do to enforce this standard？（）

A. Make sure all administrators manually change the e-mail addresses to comply with standards.
B. Instruct Active Directory administrators to change all e-mail addresses to comply with this standard.
Create an e-mail address policy.
D. Create a transport rule.