We have a policy and the Fed's mandate it (if you're involved in a Federal lawsuit you must follow this) of keeping all incoming and outgoing email related to the corporation.
We do this using Postfix's BCC configuration as follows
In your /etc/postfix/main.cf
#ZHB ADDED THE FOLLOWING PER FEDERAL GUIDLINES
sender_bcc_maps = hash:/etc/postfix/sender_bcc
recipient_bcc_maps = hash:/etc/postfix/recipient_bcc
Then in /etc/postfix/sender_bcc
Then in /etc/postfix/recipient_bcc
Then run the following
You're all set - I LOVE Linux!!!