ar_mailer memo

http://blog.segment7.net/articles/2006/08/15/ar_mailer
http://www.javaeye.com/topic/38192
http://www.hostingrails.com/forums/rails_coding_thread/150
http://www.hostingrails.com/forums/wiki_thread/2
http://drawohara.com/post/37908300/rails-using-ssl-tls-with-actionmailer-gmail#disqus_thread
http://xslforum.com/28486-re-using-actionmailer-send-email.html