#!/usr/local/perl-5.12.3/bin/perl
use strict;
use warnings;

open my $THIDS,"<", "THIDSerrs" or die "Could not open 'THIDSerrs' for reading. $!";
my %data = map {$_ => 1} <$THIDS>;
close $THIDS or die "Unable to close 'THIDSerrs' - reading. $!";

open my $mail, "<" , "mail.fil" or die "Could not open 'mail.fil' for reading. $!";
open my $out, ">", "whatever.dat" or die "Unable to open 'whatever.dat' for write. $!";

while (<$mail>) {
	print $out unless $data{$_};
}

close $mail or die "Unable to close 'mail.fil' - reading. $!";
close $out or die "Unable to close 'whatever.dat' from writing. $!";