Thanks.
I wrote a perl script and used input through to call it.
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my($addr) = $ARGV[0];
my($domain, $valid);
if ($addr =~ /^[^@]+@([-\w]+\.)+[A-Za-z]{2,4}$/) {
$domain = (split(/@/, $addr))[1];
$valid = 0;
open(DNS, "nslookup -q=any $domain |") ||...