Enable mail function per cPanel user?

I use cpanel and I turned off the mail () function on its server to prevent email spaming from this functionality, but there is one of my friend's account requires mail () function how do I allow access to mail is just the way in my friend's cpanel? so I just simply enable mail diakun itself without removing the settings on my server. can you use php.ini diakun it? if it can rule php.ini what is it like?