De-duplicate OWA emails

I need a skilled technician to de-duplicate emails from an OWA-only email account on an SBS 2011 server. All emails (both sent and received) from several unrelated accounts are forwarded to this email account on the customer's own server and when the customer searches he obviously gets multiple copies of emails that he doesn't need. What is required: - create a script to back up the current emails - create a script to reduce these emails to a manageable amount by removing all but the last email in the conversation. - the scripts should be able to be run by ourselves from time to time for future housekeeping. Would consider advice/services on a better way to handle this situation. NOTE: the importance of these emails cannot be understated so we really need someone who knows what they are doing. Do not apply if you have not done this before.