Beware, if you have MailMeter or use another product for email retention, there exists a possibility that your Journaling will be disabled if you follow all of the recommendations of the MS Best Practices Analyzer.
This one suggestion caused MailMeter to break in my environment:
1) Permissions Inheritance Block on Configuration Object
-Unblocked inheritance on Back-End Exchange server
This can be a major pain in the ass because you’ll have to setup the Journaling account again and do some other configuration. Hope you have a Support Contract.