How to use GMail SMTP server to send emails in Rails ActionMailer

Recently I had to use Ruby to send emails. I don't want to go through the hassle of setting up a mail server on my build box, and since I use GMail's hosted webmail service I am thinking I might be able to use their smtp mail server to do it.

Rail's ActionMailer was simply the automatic choice, since I am building a rails app.

Turns out GMail supports only SSL SMTP mailing service, meaning if you cannot create a SSL connection to its SMTP server, you cannot send email through them. My Rails and Ruby (1.84) version do not yet support creating a SSL SMTP connection through Net::SMTP. DHH writes about how to do so through installing msmtp here, but we developers just obviously love options =)

The dynamic nature of Ruby allows me to enhance the functionality of that class. I found the following code from a couple Japanese posts here and here on the web (fairly low Google ranking). Pasting them in my /vendor/plugins as follow:

$ cat vendor/plugins/action_mailer_tls/init.rb
require_dependency 'smtp_tls'

$ cat vendor/plugins/action_mailer_tls/lib/smtp_tls.rb
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
    @socket.debug_output = STDERR #@debug_output

    check_response(critical { recv_response() })
    do_helo(helodomain)

    raise 'openssl library not installed' unless defined?(OpenSSL)
    starttls
    ssl = OpenSSL::SSL::SSLSocket.new(sock)
    ssl.sync_close = true
    ssl.connect
    @socket = Net::InternetMessageIO.new(ssl)
    @socket.read_timeout = 60 #@read_timeout
    @socket.debug_output = STDERR #@debug_output
    do_helo(helodomain)

    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')
  end

  def quit
    begin
      getok('QUIT')
    rescue EOFError
    end
  end
end

So now, in your ActionMailer::Base's server settings if you have:

ActionMailer::Base.server_settings = {
  :address => "smtp.gmail.com",
  :port => 587,
  :domain => "mycompany.com",
  :authentication => :plain,
  :user_name => "username",
  :password => "password"
}

You call your ActionMailer::Base's deliver method (perhaps from a custom subclass), it will send an email through GMail. Mission accomplished.