Absolutely. There are a number of products and partnerships between email archiving vendors and message classification providers to help an organization set policies to determine what messages need to be archived and for how long.
You have to develop retention policies as well as message classification policies. It may seem like a difficult task but you don't want to archive spam, you don't want to archive non-business-related content. So in some cases you want to archive just the finance group. In financial services, maybe you want to archive all your brokers but you don't want to archive human resource employees.
There are ways to deploy and select what mailboxes you want to archive, and you can establish the retention period based on that. I'm a big proponent of determining what messages you want to archive and for how long before you actually get the software implemented.
Go back to the beginning of the Email Archiving in 2008 FAQ Guide.