I am using Exchange 2010 and I have an email address that is valid and sending emails to a list of users. Some of those users need to be removed, however when I search my Exchange I cannot find that email address. I tried get-mailbox -an firstname.lastname@example.org and all I get is a open prompt but no information. I searched Exchange and cannot find it. Am I missing something? How can I searched Exchange for this email. I know it's working but cannot find it.