use strict;
use warnings;
use Net::DNS;
use CGI;
use CGI::Carp qw{fatalsToBrowser};

my $q = CGI->new();

my $dns = new Net::DNS::Resolver;


if(my $domain = $q->param('domain')) {
    my $mx = $dns->query( $domain, 'MX' );

    print "content-type:text/html; charset=utf-8\n\n";
    print "$domain:\n\n";
    foreach my $rr ($mx->answer) {
        print "<br />", $rr->exchange, ' [<b>', $rr->preference, "</b>]\n";
    }
} else {
    die "missing required parameter: domain";
}