Sometime situation arises that you have to remove a message from all mailboxes as it has been accidently send & is not intended for all.

Get-mailbox -database ‘Database’ | export-mailbox –SubjectKeywords
“Confidential” -TargetFolder “ConfidentialData” -TargetMailbox
Administrator –DeleteContent

refer below for details:

http://msexchangeteam.com/archive/2006/11/28/431669.aspx