sends devise emails with delayed_jobs

Gemfile

@@ -45,6 +45,7 @@ gem 'dalli'
 gem 'rollbar', '~> 2.2.1'
 gem 'delayed_job_active_record'
 gem 'daemons'
+gem 'devise-async'
 
 gem 'ahoy_matey', '~> 1.2.1'
 gem 'groupdate'   # group temporary data

Gemfile.lock

@@ -123,6 +123,8 @@ GEM
       responders
       thread_safe (~> 0.1)
       warden (~> 1.2.3)
+    devise-async (0.10.1)
+      devise (~> 3.2)
     diff-lcs (1.2.5)
     docile (1.1.5)
     domain_name (0.5.24)
@@ -413,6 +415,7 @@ DEPENDENCIES
   database_cleaner
   delayed_job_active_record
   devise
+  devise-async
   email_spec
   factory_girl_rails
   faker

app/models/user.rb

@@ -6,7 +6,7 @@ class User < ActiveRecord::Base
 
   apply_simple_captcha
   devise :database_authenticatable, :registerable, :confirmable,
-         :recoverable, :rememberable, :trackable, :validatable, :omniauthable
+         :recoverable, :rememberable, :trackable, :validatable, :omniauthable, :async
 
   acts_as_voter
   acts_as_paranoid column: :hidden_at

config/initializers/devise_async.rb

@@ -0,0 +1,4 @@
+Devise::Async.setup do |config|
+  config.enabled = true
+  config.backend = :delayed_job
+end