You have an Exchange Server 2010 Service Pack 1 (SP1) organization.
The organization contains two mailbox-enabled users named User1 and User2.
You need to ensure that User1 can send email messages on behalf of User2.
Which cmdlet should you use?

A.
Set-MailUser

B.
Set-MailboxFolderPermissions

C.
New-TransportRule

D.
Set-Mailbox

E.
New-MailContact

F.
New-ManagementScope

G.
New-ManagementRoleAssignment

H.
Set-Group

I.
Set-ManagementRoleAssignment

J.
Add-ADPermission

Explanation:
Set-Mailbox e.g. Set-Mailbox user2 -GrantSendOnBehalfTo user1

http://technet.microsoft.com/en-us/library/bb123981.aspx