You can use an add-in for Outlook called Bells & Whistles. With this
3-rd party add-in can select to always send a BCC email to a specified
address, for each message that is going to be sent. The recipient of
the email won't see the address you chose to Auto BCC. This software
can increase a lot the productivity of working with emails.

You can find it he
http://www.emailaddressmanager.com/productivity.html