email hack

Greetings

my friend want that EVERY email sent thru wordpress to be CC to a his mail.

he wishes to have it hard coded so that this can’t be removed from admin panel

he wants it to NO be theme dependant, so I believe that functions.php is not the place to put the hook

my idea is to ‘hack’ the core mail function, and re-do the hack at each new update (pain !!)

do you see any other option?

where would you seek for in the admin for the mail function that is used everytime worpdress send a mail?

is contact form 7 use the wp build it function, since that is what I hav used for the forms?

thank you in advance for your help