#!/usr/bin/env ruby
# frozen_string_literal: true

require 'resolv'
require 'net/smtp'

def mx_records(domain)
  Resolv::DNS.open do |dns|
    dns.getresources(domain, Resolv::DNS::Resource::IN::MX)
  end
end

def mailbox_exist?(email)
  domain = email.split('@').last
  mx = mx_records(domain).first
  return false unless mx

  Net::SMTP.start(mx.exchange.to_s, 25) do |smtp|
    smtp.mailfrom 'info@example.com' # replace with your email address or something more realistic
    smtp.rcptto email
  end
  true
rescue Net::SMTPFatalError, Net::SMTPSyntaxError
  false
end

if ARGV.length != 1
  puts "Usage: ruby #{__FILE__} <email_address>"
  exit 1
end

email = ARGV[0]
if mailbox_exist?(email)
  puts "Mailbox exists."
else
  puts "Mailbox doesn't exist or couldn't be verified."
end