# environment.rb
    # Load the Rails application.
    require File.expand_path('../application', __FILE__)

    # Initialize the Rails application.
    Rails.application.initialize!

    ActionMailer::Base.smtp_settings = {
      user_name: 'your_sendgrid_username',
      password: 'your_sendgrid_password',
      domain: 'yourdomain.com',
      address: 'smtp.sendgrid.net',
      port: 587,
      authentication: :plain,
      enable_starttls_auto: true
    }

class UserMailer < ApplicationMailer
default from: 'notifications@example.com'

  def welcome_email(user)
    @user = user
    @url  = 'http://example.com/login'
    mail(to: @user.email, subject: 'Welcome to My Awesome Site')
  end
end

class UsersController < ApplicationController
  def index
    @users = User.all
  end

  def new
    @user = User.new
  end

  def create
    @user = User.new(user_params)
    if @user.save
      UserMailer.welcome_email(@user).deliver
      session[:current_user_id] = @user.token
      redirect_to root_path
    else
      render :new
    end
  end

  private

  def user_params
    params.require(:user).permit(:email, :password, :first_name, :last_name, :login)
  end
end

doctype html

html
  head
    meta content='text/html; charset=UTF-8' http-equiv='Content-Type'
  body
    Welcome to example.com,
    = @user.name
    p
      You have successfully signed up to example.com,
      your username is:
      = @user.login
    p
      To login to the site, just follow this link: = @url
    p
      Thanks for joining and have a great day!