you may use
sender_bcc_maps and
recipient_bcc_maps feature.
For example: if you want bcc of all outgoing message, you may create a file with any name in /etc/postfix with something like this:
Code:
*@domain1.com mailaddress@domain1.com
*@domain2.com mailaddress@domain2.com
then run
Code:
postmap /etc/postfix/filename
and
add following line to
/etc/postfix/main.cf
Code:
sender_bcc_maps = hash:/etc/postfix/filename
Similar for recipient_bcc_maps.
then, restart postfix
You may find details at
http://www.postfix.org/postconf.5.html