使用TLS从Ruby程序发送电子邮件

#!/usr/bin/ruby

require 'rubygems'
require 'net/smtp'

msgstr = "Test email."

smtp = Net::SMTP.start('smtp.server.com',587,'mail.server.com','username','password',:login) do |smtp|
    smtp.send_message msgstr,'from@server.com','to@server.com'
end

当我运行这个时,我得到以下错误.

/usr/lib/ruby/1.8/net/smtp.rb:948:in `check_auth_continue': 
530 5.7.0 Must issue a STARTTLS command first (Net::SMTPAuthenticationError)
    from /usr/lib/ruby/1.8/net/smtp.rb:740:in `auth_login'
    from /usr/lib/ruby/1.8/net/smtp.rb:921:in `critical'
    from /usr/lib/ruby/1.8/net/smtp.rb:739:in `auth_login'
    from /usr/lib/ruby/1.8/net/smtp.rb:725:in `send'
    from /usr/lib/ruby/1.8/net/smtp.rb:725:in `authenticate'
    from /usr/lib/ruby/1.8/net/smtp.rb:566:in `do_start'
    from /usr/lib/ruby/1.8/net/smtp.rb:525:in `start'
    from /usr/lib/ruby/1.8/net/smtp.rb:463:in `start'

我在Ruby api for Net::SMTP引用TLS或STARTTLS命令中找不到任何内容.

编辑：
下载smtp-tls.rb,代码没有太大变化,但这是我的工作.

#!/usr/bin/ruby

require 'rubygems'
require 'net/smtp'
require 'smtp-tls'

msgstr = <<MESSAGE_END
From: me <me@test.com>
To: you <you@test.com>
Subject: e-mail test

body of email

MESSAGE_END

smtp = Net::SMTP.start('smtp.test.com','test.com','passwd','me@test.com',['you@test.com']
end

编辑：与ruby 1.8.6一起使用