Email scanning software

I'm seeking software that will scan emails for specific words and phrases. The software should work with Outlook/MS Exchange and possibly Gmail. The local admin should be able to type in a set of email usernames and passwords, and a set of phrases. The software should then search for the existence of such phrases. The software should produce a report (preferably emailed to the admin) stating whether any such phrases were found. By default the software should perform the search weekly for the last week’s emails. The admin should also be able to search emails for specific start and end dates. The software should provide product activation, to ensure that it will search for a maximum number of email addresses. Please state how you would approach this project. I will need reassurance that you have a methodology that will work.