#!/usr/bin/perl
use strict;
use warnings;

my $line;
my $domain = shift || "";

my ($from) = map /^From:.*[< 	]([\w.-]+\@([\w.-]+\.)+\w+)>?/, <>;

if($domain eq "--domain") {
  $from =~ s/.*@//;
}

print "$from\n" if ($from);