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?