gistfile1.rb

class UsersController < ApplicationController
  def create
    @user = User.new params[:user]
    @user.save
    respond_to do |format|
      format.html do
        EmailService.send_welcome_email user
        redirect_to @user
      end
      format.json do
        render :json => @user,
          :status => :created,
          :location => @user
      end
    end
  end
end

class EmailService
  def self.send_welcome_email(user)
    email = UserMailer.welcome_email user
    email.deliver
  end
end