title: uninitialized constant PurchasesController::UserMailer
body: <p>I've generated a mailer for an Order confirmation. I'm getting a NameError at /purchases.
  The error reads:</p>
  
  <pre><code>uninitialized constant PurchasesController::UserMailer
    /controllers/purchases_controller.rb
  
   class PurchasesController &lt; InheritedResources::Base
     before_filter :authenticate_admin_user!, :only =&gt; [:index, :edit, :update, :destroy]
  
     def create
       @purchase = Purchase.new(params[:purchase])
       if @purchase.save
         UserMailer.purchase_confirmation(@purchase).deliver
         redirect_to "/thankyou"
       else     
         render :action =&gt; "new"
       end
  </code></pre>
  
  <p>I've been digging around and have found similar issues, but nothing as of yet to solve my problem. Any help?</p>