[exim] How exim track email sent per hour per domain users

Hi, all.

I am using cPanel with Exim. cPanel use /etc/exim.pl and /etc/exim.pl.local
for limit email sent per hour per domain users. From /etc/exim.pl.local I
see it get current email sent per hour from
folder /var/cpanel/email_send_limits/track/ .

I wonder to know how exim track and count email sent by user ? Where file
do it ? I want to know file because I want to change exim track. I want to
track only email sent to another server not domain in local server.

Sorry for my poor english. Thank you !