It is quite logical to track all important activities in the mailbox as if a single message is deleted intentionally or unintentionally, it could lead to direct loss in revenue with probability of account loss.
To handle this kind of requirements MS Exchange Server 2010 comes
This script is tested on these platforms by the author. It is likely to work on other platforms as well. If you try it and find that it works on another platform, please add a note to the script discussion to let others know.