Verify email addresses

verifyemail.js

var _ = require('underscore'),
  exec = require('child_process').exec,
  net = require('net'),
  email = process.argv.splice(2)[0],
  domain = email.split('@')[1];

function verify(mxrecord) {
  console.log('connecting to', mxrecord);
  var conn = net.createConnection(25, mxrecord),
    commands = [
      'HELO ' + mxrecord,
      'mail from:<notifications@foobar.com>',
      'rcpt to:<' + email + '>'
    ],
    i = 0;

  conn.setEncoding('ascii');
  conn.on('connect', function () {
    console.log('connected successfully');
  });
  conn.on('data', function (data) {
    console.log(data)
    if (i >= commands.length) {
      if ((/ok\s|okay/).test(data.toLowerCase())) {
        console.log(email, 'appears to be valid');
      } else {
        console.error(data);
      }
      conn.end();
      return;
    }
    console.log(commands[i]);
    var message = conn.write(commands[i] + '\n');
    if (!message) {
      console.error('error sending last message');
      process.exit(1);
    }
    i += 1;
  });
  conn.on('error', function () {
    console.error('error', arguments);
  });
  conn.on('end', function () {
    process.exit(0);
  });
}

exec('nslookup -type=MX ' + domain, function (err, stdout, stderr) {
  var records = _.reject(stdout.split(/\n/), function (l) {
      return l.indexOf(domain) !== 0 || l.indexOf('exchanger') === -1;
    }).sort(function (a, b) {
      var a = a.split(/\s+/)[4],
        b = b.split(/\s+/)[4];
      return ~~a - ~~b;
    }),
    record;

    if (!records.length) {
      console.log('no records');
      console.log(records);
      process.exit(1);
    }
    record = _.last(_.first(records).split(/\s+/)).replace(/\.$/, '');

    verify(record);
});