require "openssl"
require "net/smtp"
Net::SMTP.class_eval do
  private
  def do_start(helodomain, user, secret, authtype)
    raise IOError, 'SMTP session already started' if @started
    check_auth_args user, secret, authtype if user or secret
 
    sock = timeout(@open_timeout) { TCPSocket.open(@address, @port) }
    @socket = Net::InternetMessageIO.new(sock)
    @socket.read_timeout = 60 #@read_timeout
 
    check_response(critical { recv_response() })
    do_helo(helodomain)
 
    if starttls
      raise 'openssl library not installed' unless defined?(OpenSSL)
      ssl = OpenSSL::SSL::SSLSocket.new(sock)
      ssl.sync_close = true
      ssl.connect
      @socket = Net::InternetMessageIO.new(ssl)
      @socket.read_timeout = 60 #@read_timeout
      do_helo(helodomain)
    end
 
    authenticate user, secret, authtype if user
    @started = true
  ensure
    unless @started
      # authentication failed, cancel connection.
      @socket.close if not @started and @socket and not @socket.closed?
      @socket = nil
    end
  end
 
  def do_helo(helodomain)
     begin
      if @esmtp
        ehlo helodomain
      else
        helo helodomain
      end
    rescue Net::ProtocolError
      if @esmtp
        @esmtp = false
        @error_occured = false
        retry
      end
      raise
    end
  end
 
  def starttls
    getok('STARTTLS') rescue return false
    return true
  end
 
  def quit
    begin
      getok('QUIT')
    rescue EOFError
    end
  end
end

# config/initializers/mailer.rb
 
require "#{RAILS_ROOT}/lib/smtp_tls"
 
ActionMailer::Base.delivery_method = :smtp
ActionMailer::Base.smtp_settings = { 
  :address => "smtp.gmail.com",  
  :port => 587, 
  :domain => "domain.com", 
  :user_name => "no-reply@domain.com", 
  :password => "kPBHSarYNVugAPoE", 
  :authentication => :plain
}