Rails Mailing

development.rb

# add this to the file
config.action_mailer.delivery_method = :letter_opener

production.rb

Rails.application.configure do
  ActionMailer::Base.smtp_settings = {
    :port =>           '587',
    :address =>        'smtp.mandrillapp.com',
    :user_name =>      ENV['MANDRILL_USERNAME'],
    :password =>       ENV['MANDRILL_APIKEY'],
    :domain =>         'heroku.com',
    :authentication => :plain
  }

  ActionMailer::Base.delivery_method = :smtp
end

user.rb

class User < ActiveRecord::Base
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable

  after_create :send_welcome_email

  private

  def send_welcome_email
    UserMailer.welcome(self).deliver
  end
end

user_mailer.rb

class UserMailer < ApplicationMailer
  default from: 'user@domain.com'

  def welcome(user)
    # make the user available for the view (it needs to be an instance variable for this)
    @user = user

    # this will render the view in app/views/user_mailer
    mail(to: @user.email, subject: 'Welcome to this demo')
  end
end

welcome.html.erb

Hi <%= @user.name %>,

Today we'll talk about SMTP and Mandrill!

See ya!