bcc specific user's emails

A client has asked me to bcc all outgoing emails from three specific users to him. The Server Configuration->Email Settings only allows me to specify a destination address for all emails.

I tried re-editing the bcc file in /etc/postfix to

user1@domain.com recipient@domain.com
user2@domain.com recipient@domain.com
user3@domain.com recipient@domain.com

I then ran postmap on the bcc file to create a bcc.db

When I go back to the settings however, the bcc option has been removed/turned off.

Any ideas?

Graham Bevins