api.rb

  def unsubscribe
    token = Base64.decode64(params[:token])    #using base64 encoding in the url to prevent unsubscribe abuse
    @user = User.find_by_access_token(token)                #find the user from the ID in url
    @user.opt_out = true                     #change them to not get email
    @user.save                                #save the changes
    redirect_to "/", :notice => "We won't bug you with emails!"       #give them a little notice that it worked
  end