Action Mailer does not send mails at all

Rails 3.1.3

I have followed the RailsCast ActionMailer.
http://railscasts.com/episodes/206-action-mailer-in-rails-3
Around 5minutes, Ryan succeeds in sending mails, but I don't.

My setup_mail.rb

ActionMailer::Base.smtp_settings = {
  :address => "smtp.gmail.com",
  :port => 587,
  :domain => "gmail.com",
  :user_name => "soujiro0725@gmail.com",
  :password => "xxx",
  :authentication => "plain",
  :enable_starttls_auto => true
}

I added to users_controller.rb

        UserMailer.registration_confirmation(@user).deliver

and user_mailer.rb

class UserMailer < ActionMailer::Base
  default from: "from@example.com"
  def registration_confirmation(user)
    mail(:to => user.email, :subject => "Registered" )

  end
end

and I prepared registration_confirmation.txt.erb

Could anyone find what's wrong with it ?

Thanks in advance.

soichi

What happens when you run the following in the console?

user = User.first
UserMailer.registration_confirmation(user).deliver