#!/usr/local/bin/perl
open (infile,$ARGV[0]);
while ($line=<infile>) {
	chop $line;
	foreach $x (`nslookup -query=mx $line`) {
		if ($x =~ /mail exchanger/i) {
			($x1,$x2,$host)=split (/=/,$x);
			print "$host";
		}
	}
}