You can make sure of Messaging Records Management feature in Exchange 2007. Technet article below provides more details and implementation steps. http://technet.microsoft.com/en-us/library/bb123548(v=exchg.80)

Hi, I have a very few users in my organization that I need to create a policy for. They access their mailbox via smartphone only, and only to their Inbox. Is it possible to create a policy that will automatically deletes all email in the "deleted items" and "sent items" folders? (We use Exchange 2007). If so, can anyone guide me how? Thank, Moriya :)

You can make sure of Messaging Records Management feature in Exchange 2007. Technet article below provides more details and implementation steps. http://technet.microsoft.com/en-us/library/bb123548(v=exchg.80)

Hi You can create managed Folder Mailbox policy link to delete\sent item folder and apply it to users. You can read this blog of it. There is offical document. http://technet.microsoft.com/en-us/library/aa996359(v=exchg.80).aspxTerence Yu TechNet Community Support