Enviar e-mail

send_mail.rb

require 'mail'

Mail.defaults do
  delivery_method :smtp, {
    :address              => '<smtp server>',
    :port                 => 587,
    :user_name            => '<username>',
    :password             => '<password>',
    :authentication       => 'plain',
    :enable_starttls_auto => true  }
end
mail = Mail.new do
  from     '<from mail address>'
  to       '<to mail address>'
  subject  '<subject>'
  body     '<message>'
end

mail.deliver!

Realmente, é assim:

require 'mail'
options = { :address              => "smtp.gmail.com",
            :port                 => 587,
            :domain               => 'your.host.name',
            :user_name            => '<username>',
            :password             => '<password>',
            :authentication       => 'plain',
            :enable_starttls_auto => true  }

Mail.defaults do
  delivery_method :smtp, options
end

Passa o bloco e o hash vem nos options.

foi assim que eu fiz, só não criei a variável options :p