We are trying to change the default retention period that is currently applied to all email in our Exchange 2010 server. It was originally set for 10 years, 3650 days, and we are changing that to 2 years, 730 days. We have made the change, however; all old items and even new items are still marked with the 10 year retention time. How do we get the messages to take the new 2 year retention period; even those messages previously marked for the longer retention time? Also, why aren't the new messages being marked with the new 2 year retention period? Any help is appreciated.