This video provides step by step instructions for how to configure MRM after enabling an archive mailbox. For additional information, please see the following link.
Overall overview for MRM: https://technet.microsoft.com/en-us/library/dd335093(v=exchg.150).aspx Steps for MRM: https://technet.microsoft.com/en-us/library/jj150558(v=exchg.150).aspx
