TypeError (Mail is not a module)

I stepped through the introduction on Action Mailer Basics here:

         http://edgeguides.rubyonrails.org/action_mailer_basics.html

up through 2.1.3,

In 2.1.4, I already had a user class, so I just copied the line

        UserMailer.welcome_email(@user).deliver

into my user_controller/action, modifying it to

        UserMailer.welcome_email(user, contact).deliver

since I had a user and a contact I wished to reference from the body
of the email message.

When the application tries to execute that line I get the following
error:

        TypeError (Mail is not a module):

          app/mailers/user_mailer.rb:1:in `<top (required)>'

          app/controllers/users_controller.rb:285:in `mail_contact'

          app/controllers/users_controller.rb:409:in `add_contact'

user_mailer.rb looks like this: