Hire a very good lawyer (for the company) and look for a new job...
if he wants to see what's going thru the system then create an agent in both the incoming and outgoing mailbox's on the server to send a copy to him of each mail. Unless you are a pretty small shop with little internet usage that'll last a bout a week. Otherwise you could have a copy of each message sent to an archive DB, which could be reviewed as needed. Or you could take away the users rights to delete documents or archive from their own mailboxes and make tape copies of each mailbox routinely.
If he actually wants to approve each piece of mail then change the in and out boxes to send the mail by manual action versus agent, give him access and let him go in and do his stuff.