email validation in ruby

quick_email_validator.rb

require 'resolv'
require 'rubygems'
require 'sequel'
def validate_email_domain(email)
  domain = email.match(/\@(.+)/)[1]
  Resolv::DNS.open do |dns|
    @mx = dns.getresources(domain, Resolv::DNS::Resource::IN::MX)
  end
  @mx.size > 0 ? true : false
end

DB = Sequel.mysql(:host => 'localhost', :user => 'user', :password => 'password', :database => 'database')
subscribers = DB[:previous_email_list_table]
validated = DB[:validated]

subscribers.each do |sub|
  puts "Validating email number #{sub[:id]}"
  validator = validate_email_domain(sub[:email])
  if validator == true
    validated.insert(:id => nil, :email => sub[:email], :firstname => sub[:first_name], :lastname => sub[:last_name])
  end
end

validated.sql

CREATE TABLE `validated` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `email` varchar(255) NOT NULL,
  `firstname` varchar(255) DEFAULT NULL,
  `lastname` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=1 DEFAULT CHARSET=latin1