Exim embedded exim.pl vs exim.local.pl

Hello, When exim.pl or exim.local.pl runs? Is there any precedence on which one is called first? I would like to add some custom filters for outbound remote emails but I am not sure where to start adding my subroutines. I could not find documentation on cPanel regarding this case. Currently I am doing a perl_startup do '/etc/custom_filters.pl' And custom_filters content is: ######## open(my $fd, ">>/var/log/custom_exim.log"); my $from_h = "$from_h_localpart\@$from_h_domain"; print $fd "from_h_domain: $from_h \n"; do "/etc/exim.pl"; 1; ######## I am not getting logs when sending from authenticated smtp users but I do get logs on local mails sent by scripts. I appreciate if someone can clarify this for me. Thank you.