#!/usr/bin/perl
use strict;
use LWP::Simple qw( get );

while (1) {
my $mail = get("http://url.org/goes/here");
$mail =~ /MAIL: (YES|NO)/;
my $status = $1;

if ($status eq "YES") {
system("br a1 on");
} else {
system("br a1 off");
}

sleep(20);

}