New to Perl Help and bmail

I have a pl script that runs on a server that triggers bmail to send
several emails. I cannot figure out where bmail is getting its
parameters . It is the transmit command that is triggering the event
but where are the parameters coming from? Here is the script

use strict;
use CGI ':standard';

#External perl functions are referenced here.

require 'extsub.pl';

my $filename = param('filename');
my $office1 = param('office1');
my $office2 = param('office2');
my $client = param('client');
my $techmail = param('techmail');
my $tech = param('tech');

#Begin to build HTML by perl functions.

mime();
heading("Transmission Complete!");

print 'Attempting to transmit...errors listed here will be
from bmail software.