diff --git a/.gitignore b/.gitignore
index 80b096a..866b771 100644
--- a/.gitignore
+++ b/.gitignore
@@ -33,3 +33,6 @@
 config/settings.local.yml
 config/settings/*.local.yml
 config/environments/*.local.yml
+
+# Ignore application configuration
+/config/application.yml
diff --git a/Gemfile b/Gemfile
index 06f6764..3d72e7c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -10,6 +10,7 @@ gem "bootstrap-will_paginate", "1.0.0"
 gem "coffee-rails", "~> 4.2"
 gem "config"
 gem "faker", "1.9.1"
+gem "figaro"
 gem "jbuilder", "~> 2.5"
 gem "jquery-rails", "~> 4.3", ">= 4.3.3"
 gem "puma", "~> 3.11"
diff --git a/Gemfile.lock b/Gemfile.lock
index 03bb1f1..f39b4b1 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -103,6 +103,8 @@ GEM
     faker (1.9.1)
       i18n (>= 0.7)
     ffi (1.9.25)
+    figaro (1.1.1)
+      thor (~> 0.14)
     globalid (0.4.1)
       activesupport (>= 4.2.0)
     i18n (1.0.1)
@@ -238,6 +240,7 @@ DEPENDENCIES
   coffee-rails (~> 4.2)
   config
   faker (= 1.9.1)
+  figaro
   jbuilder (~> 2.5)
   jquery-rails (~> 4.3, >= 4.3.3)
   listen (>= 3.0.5, < 3.2)
diff --git a/app/controllers/account_activations_controller.rb b/app/controllers/account_activations_controller.rb
new file mode 100644
index 0000000..ae675ac
--- /dev/null
+++ b/app/controllers/account_activations_controller.rb
@@ -0,0 +1,14 @@
+class AccountActivationsController < ApplicationController
+  def edit
+    user = User.find_by email: params[:email]
+    if user && !user.activated? && user.authenticated?(:activation, params[:id])
+      user.activated
+      log_in user
+      flash[:success] = t "account_activated"
+      redirect_to user
+    else
+      flash[:danger] = t "account_activate_invalid"
+      redirect_to root_url
+    end
+  end
+end
diff --git a/app/controllers/sessions_controller.rb b/app/controllers/sessions_controller.rb
index 3d8a34e..03428d7 100644
--- a/app/controllers/sessions_controller.rb
+++ b/app/controllers/sessions_controller.rb
@@ -4,9 +4,16 @@ def new; end
   def create
     @user = User.find_by email: params[:session][:email].downcase
     if @user&.authenticate params[:session][:password]
-      log_in @user
-      remember_me
-      redirect_back_or @user
+      if @user.activated?
+        log_in @user
+        remember_me
+        redirect_back_or @user
+      else
+        message  = t "activation_message1"
+        message += t "activation_message2"
+        flash[:warning] = message
+        redirect_to root_url
+      end
     else
       flash.now[:danger] = t ".error_login"
       render :new
diff --git a/app/controllers/users_controller.rb b/app/controllers/users_controller.rb
index df99185..af682e6 100644
--- a/app/controllers/users_controller.rb
+++ b/app/controllers/users_controller.rb
@@ -4,7 +4,7 @@ class UsersController < ApplicationController
   before_action :correct_user, only: [:edit, :update]
   before_action :admin_user, only: :destroy
   def index
-    @users = User.paginate page: params[:page],
+    @users = User.where(activated: true).paginate page: params[:page],
                            per_page: Settings.total_user_per_page
   end
 
@@ -15,15 +15,17 @@ def new
   def create
     @user = User.new user_params
     if @user.save
-      log_in @user
-      flash[:success] = t ".title_sample"
-      redirect_to @user
+      @user.send_activation_email
+      flash[:info] = t "activation_mesage"
+      redirect_to root_url
     else
       render :new
     end
   end
 
-  def show; end
+  def show
+    redirect_to(root_url) && return unless @user.activated == true
+  end
 
   def edit; end
 
diff --git a/app/helpers/account_activations_helper.rb b/app/helpers/account_activations_helper.rb
new file mode 100644
index 0000000..c4d5ac7
--- /dev/null
+++ b/app/helpers/account_activations_helper.rb
@@ -0,0 +1,2 @@
+module AccountActivationsHelper
+end
diff --git a/app/helpers/sessions_helper.rb b/app/helpers/sessions_helper.rb
index b093be3..87cedc8 100644
--- a/app/helpers/sessions_helper.rb
+++ b/app/helpers/sessions_helper.rb
@@ -18,7 +18,7 @@ def current_user
       @current_user ||= User.find_by id: user_id
     elsif user_id = cookies.signed[:user_id]
       user = User.find_by id: user_id
-      if user&.authenticated? cookies[:remember_token]
+      if user&.authenticated?(:remember, cookies[:remember_token])
         log_in user
         @current_user = user
       end
diff --git a/app/mailers/application_mailer.rb b/app/mailers/application_mailer.rb
index 3c34c81..115c49c 100644
--- a/app/mailers/application_mailer.rb
+++ b/app/mailers/application_mailer.rb
@@ -1,4 +1,4 @@
 class ApplicationMailer < ActionMailer::Base
-  default from: "from@example.com"
+  default from: "duong147nguyen@gmail.com"
   layout "mailer"
 end
diff --git a/app/mailers/user_mailer.rb b/app/mailers/user_mailer.rb
new file mode 100644
index 0000000..7ea11e1
--- /dev/null
+++ b/app/mailers/user_mailer.rb
@@ -0,0 +1,12 @@
+class UserMailer < ApplicationMailer
+  def account_activation user
+    @user = user
+    mail to: user.email, subject: t("account_activation")
+  end
+
+  def password_reset
+    @greeting = "Hi"
+
+    mail to: "to@example.org"
+  end
+end
diff --git a/app/models/user.rb b/app/models/user.rb
index c2df066..220ed88 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -1,7 +1,9 @@
 class User < ApplicationRecord
   VALID_EMAIL_REGEX = /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
   attr_reader :remember_token
+  attr_accessor :activation_token
   before_save :email_downcase
+  before_create :create_activation_digest
   has_secure_password
 
   validates :name,  presence: true,
@@ -18,9 +20,10 @@ def remember
     update_attributes remember_digest: User.digest(remember_token)
   end
 
-  def authenticated? remember_token
-    return false if remember_digest.nil?
-    BCrypt::Password.new(remember_digest).is_password?(remember_token)
+  def authenticated? attribute, token
+    digest = send "#{attribute}_digest"
+    return false if digest.nil?
+    BCrypt::Password.new(digest).is_password? token
   end
 
   def forget
@@ -31,6 +34,14 @@ def current_user? user
     user == self
   end
 
+  def activated
+    update_columns activated: true, activated_at: Time.zone.now
+  end
+
+  def send_activation_email
+    UserMailer.account_activation(self).deliver_now
+  end
+
   class << self
     def digest string
       cost = if ActiveModel::SecurePassword.min_cost
@@ -51,4 +62,9 @@ def new_token
   def email_downcase
     self.email = email.downcase
   end
+
+  def create_activation_digest
+    self.activation_token  = User.new_token
+    self.activation_digest = User.digest activation_token
+  end
 end
diff --git a/app/views/user_mailer/account_activation.html.erb b/app/views/user_mailer/account_activation.html.erb
new file mode 100644
index 0000000..32f2027
--- /dev/null
+++ b/app/views/user_mailer/account_activation.html.erb
@@ -0,0 +1,8 @@
+<h1><%= t ".title" %></h1>
+
+<p><%= t ".hi" %><%= @user.name %>,</p>
+
+<p><%= t ".welcome" %></p>
+
+<%= link_to t(".active"), edit_account_activation_url(id: @user.activation_token,
+                                                      email: @user.email) %>
diff --git a/app/views/user_mailer/account_activation.text.erb b/app/views/user_mailer/account_activation.text.erb
new file mode 100644
index 0000000..7584fec
--- /dev/null
+++ b/app/views/user_mailer/account_activation.text.erb
@@ -0,0 +1,5 @@
+<%= t ".hi" %><%= @user.name %>,
+
+<%= t ".welcome" %>
+
+<%= edit_account_activation_url(id: @user.activation_token, email: @user.email) %>
diff --git a/app/views/user_mailer/password_reset.html.erb b/app/views/user_mailer/password_reset.html.erb
new file mode 100644
index 0000000..6dec984
--- /dev/null
+++ b/app/views/user_mailer/password_reset.html.erb
@@ -0,0 +1,5 @@
+<h1>User#password_reset</h1>
+
+<p>
+  <%= @greeting %>, find me in app/views/user_mailer/password_reset.html.erb
+</p>
diff --git a/app/views/user_mailer/password_reset.text.erb b/app/views/user_mailer/password_reset.text.erb
new file mode 100644
index 0000000..5ba80cc
--- /dev/null
+++ b/app/views/user_mailer/password_reset.text.erb
@@ -0,0 +1,3 @@
+User#password_reset
+
+<%= @greeting %>, find me in app/views/user_mailer/password_reset.text.erb
diff --git a/config/application.rb b/config/application.rb
index f6c370b..4f560e5 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -23,5 +23,6 @@ class Application < Rails::Application
     config.load_defaults 5.2
     config.i18n.default_locale = :vi
     config.generators.system_tests = nil
+
   end
 end
diff --git a/config/environments/development.rb b/config/environments/development.rb
index 1311e3e..9e456de 100644
--- a/config/environments/development.rb
+++ b/config/environments/development.rb
@@ -1,25 +1,16 @@
 Rails.application.configure do
-  # Settings specified here will take precedence over those in config/application.rb.
-
-  # In the development environment your application's code is reloaded on
-  # every request. This slows down response time but is perfect for development
-  # since you don't have to restart the web server when you make code changes.
   config.cache_classes = false
 
-  # Do not eager load code on boot.
   config.eager_load = false
 
-  # Show full error reports.
   config.consider_all_requests_local = true
 
-  # Enable/disable caching. By default caching is disabled.
-  # Run rails dev:cache to toggle caching.
-  if Rails.root.join('tmp', 'caching-dev.txt').exist?
+  if Rails.root.join("tmp", "caching-dev.txt").exist?
     config.action_controller.perform_caching = true
 
     config.cache_store = :memory_store
     config.public_file_server.headers = {
-      'Cache-Control' => "public, max-age=#{2.days.to_i}"
+      "Cache-Control" => "public, max-age=#{2.days.to_i}"
     }
   else
     config.action_controller.perform_caching = false
@@ -27,35 +18,34 @@
     config.cache_store = :null_store
   end
 
-  # Store uploaded files on the local file system (see config/storage.yml for options)
   config.active_storage.service = :local
 
-  # Don't care if the mailer can't send.
-  config.action_mailer.raise_delivery_errors = false
-
-  config.action_mailer.perform_caching = false
+  # Don"t care if the mailer can"t send.
+  config.action_mailer.raise_delivery_errors = true
+  host = "localhost:3000"                     # Local server
+  config.action_mailer.delivery_method = :smtp
+  config.action_mailer.default_url_options = { host: host, protocol: "http" }
+  config.action_mailer.smtp_settings = {
+    address: "smtp.gmail.com",
+    port: "587",
+    authentication: :plain,
+    user_name: ENV["mail_username"],
+    password: ENV["mail_password"],
+    enable_starttls_auto: true,
+    domain: "gmail.com"
+  }
+
+  config.action_mailer.perform_caching = true
 
-  # Print deprecation notices to the Rails logger.
   config.active_support.deprecation = :log
 
-  # Raise an error on page load if there are pending migrations.
   config.active_record.migration_error = :page_load
 
-  # Highlight code that triggered database queries in logs.
   config.active_record.verbose_query_logs = true
 
-  # Debug mode disables concatenation and preprocessing of assets.
-  # This option may cause significant delays in view rendering with a large
-  # number of complex assets.
   config.assets.debug = true
 
-  # Suppress logger output for asset requests.
   config.assets.quiet = true
 
-  # Raises error for missing translations
-  # config.action_view.raise_on_missing_translations = true
-
-  # Use an evented file watcher to asynchronously detect changes in source code,
-  # routes, locales, etc. This feature depends on the listen gem.
   config.file_watcher = ActiveSupport::EventedFileUpdateChecker
 end
diff --git a/config/locales/en.yml b/config/locales/en.yml
index d90d5c8..0a5a535 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -6,6 +6,12 @@ en:
   delete_mesage_success: "User deleted"
   delete_mesage_failed: "User delete failed"
   login_message: "Please log in."
+  account_activation: "Account activation"
+  account_activated: "Account activated!"
+  account_activate_invalid: "Invalid activation link"
+  activation_message1: "Account not activated. "
+  activation_message2: "Check your email for the activation link."
+  activation_mesage: "Please check your email to activate your account."
   static_pages:
     home:
       title: "Home"
@@ -95,3 +101,10 @@ en:
       new_user: "New user ?"
     create:
       error_login: "Invalid email/password combination"
+  user_mailer:
+    account_activation:
+      title: "Sample App"
+      hi: "Hi "
+      welcome: "Welcome to the Sample App! Click on the link below to activate your account:"
+      active: "Activate"
+
diff --git a/config/locales/vi.yml b/config/locales/vi.yml
index 67590b4..af57174 100644
--- a/config/locales/vi.yml
+++ b/config/locales/vi.yml
@@ -6,6 +6,12 @@ vi:
   delete_mesage_success: "Người dùng đã xóa"
   delete_mesage_failed: "Người dùng chưa được xóa"
   login_message: "Làm ơn hay đăng nhập."
+  account_activation: "Kích hoạt tài khoản"
+  account_activated: "Tài khoản đã được kích hoạt!"
+  account_activate_invalid: "Đường dẫn kích hoạt không đúng"
+  activation_message1: "Tài khoản chưa được kích hoạt. "
+  activation_message2: "Kiểm trai thư của bạn để có thể kích hoạt."
+  activation_mesage: "Vui lòng kiểm tra email của bạn để kích hoạt tài khoản của bạn."
   will_paginate:
     next_label: "Sau"
     previous_label: "Trước"
@@ -114,3 +120,9 @@ vi:
       new_user: "Người dùng mới ?"
     create:
       error_login: "Email không tồn tại/mật khẩu sai"
+  user_mailer:
+    account_activation:
+      title: "Ứng dụng mẫu"
+      hi: "Chào "
+      welcome: "Chào mừng bạn đến với Ứng dụng mẫu! Nhấp vào liên kết bên dưới để kích hoạt tài khoản của bạn:"
+      active: "Kích hoạt"
diff --git a/config/routes.rb b/config/routes.rb
index 889b8fe..0e3e6a4 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -10,5 +10,6 @@
     post "/login", to: "sessions#create"
     delete "/logout", to: "sessions#destroy"
     resources :users
+    resources :account_activations, only: [:edit]
   end
 end
diff --git a/db/migrate/20180722125049_add_activation_to_users.rb b/db/migrate/20180722125049_add_activation_to_users.rb
new file mode 100644
index 0000000..9bf56f4
--- /dev/null
+++ b/db/migrate/20180722125049_add_activation_to_users.rb
@@ -0,0 +1,7 @@
+class AddActivationToUsers < ActiveRecord::Migration[5.2]
+  def change
+    add_column :users, :activation_digest, :string
+    add_column :users, :activated, :boolean, default: false
+    add_column :users, :activated_at, :datetime
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 26687bc..d489b1e 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2018_07_20_021324) do
+ActiveRecord::Schema.define(version: 2018_07_22_125049) do
 
   create_table "users", force: :cascade do |t|
     t.string "name"
@@ -20,6 +20,9 @@
     t.string "password_digest"
     t.string "remember_digest"
     t.boolean "admin", default: false
+    t.string "activation_digest"
+    t.boolean "activated", default: false
+    t.datetime "activated_at"
     t.index ["email"], name: "index_users_on_email", unique: true
   end
 
diff --git a/db/seeds.rb b/db/seeds.rb
index 6c43df1..fe79f81 100644
--- a/db/seeds.rb
+++ b/db/seeds.rb
@@ -2,7 +2,9 @@
              email: "example@railstutorial.org",
              password: "foobar",
              password_confirmation: "foobar",
-             admin: true)
+             admin: true,
+             activated: true,
+             activated_at: Time.zone.now)
 
 99.times do |n|
   name  = Faker::Name.name
@@ -11,5 +13,7 @@
   User.create!(name:  name,
                email: email,
                password: password,
-               password_confirmation: password)
+               password_confirmation: password,
+               activated: true,
+               activated_at: Time.zone.now)
 end