Simple e-mail address validator script that makes a request to e-mail adress' smtp server.

email_validator.rb

#
# email_validator.rb
#
# Simple e-mail address validator script that makes a request to e-mail adress' smtp server.
#

# Released under MIT license.

# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:

# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

def is_email_address_valid?(input)
	require 'resolv'
	mail_servers = Resolv::DNS.open.getresources(input.split('@')[1], Resolv::DNS::Resource::IN::MX)
	if mail_servers.empty?
	  return false
	else
	    require 'net/smtp'	  
	    mail_servers.each do |mail_server|
		  Net::SMTP.start(mail_server.exchange.to_s, 25) do |smtp|
		  	if smtp.helo("jurajmasar.com").status == '250'
		  		smtp.mailfrom("test@jurajmasar.com")
		  		begin		  			
		  			return true if smtp.rcptto(input).status == '250'
		  		rescue
		  			return false
		  		end
		  	else
		  		next
		  	end	
		  end
	   end
	end
end

puts is_email_address_valid? ARGV[0]