Add mailing via Mailgun

.gitignore

 
 # Ignore IDEA
 .idea
+
+# Ignore secrets
+.rbenv-vars

.rbenv-vars-sample

+MAILGUN_DOMAIN=
+MAILGUN_API_KEY=
+
+MAIL_FROM_ADDRESS=

Gemfile

 # Use YARD for documentation
 gem 'yard'
 
+# Use Mailgun for mail
+gem 'mailgun_rails'
+
 # Use Capistrano for deployment
 # gem 'capistrano-rails', group: :development
 

Gemfile.lock

     coffee-script-source (1.11.1)
     concurrent-ruby (1.0.2)
     debug_inspector (0.0.2)
+    domain_name (0.5.20161129)
+      unf (>= 0.0.5, < 1.0.0)
     erubis (2.7.0)
     execjs (2.7.0)
     faker (1.7.2)
       activesupport (>= 4.1.0)
     haml (4.0.7)
       tilt
+    http-cookie (1.0.3)
+      domain_name (~> 0.5)
     i18n (0.7.0)
     jbuilder (2.6.1)
       activesupport (>= 3.0.0, < 5.1)
       rails-dom-testing (>= 1, < 3)
       railties (>= 4.2.0)
       thor (>= 0.14, < 2.0)
+    json (2.0.3)
     listen (3.0.8)
       rb-fsevent (~> 0.9, >= 0.9.4)
       rb-inotify (~> 0.9, >= 0.9.7)
       nokogiri (>= 1.5.9)
     mail (2.6.4)
       mime-types (>= 1.16, < 4)
+    mailgun_rails (0.9.0)
+      actionmailer (>= 3.2.13)
+      json (>= 1.7.7)
+      rest-client (>= 1.6.7)
     method_source (0.8.2)
     mime-types (3.1)
       mime-types-data (~> 3.2015)
     mini_portile2 (2.1.0)
     minitest (5.10.1)
     multi_json (1.12.1)
+    netrc (0.11.0)
     nio4r (1.2.1)
     nokogiri (1.6.8.1)
       mini_portile2 (~> 2.1.0)
     rb-fsevent (0.9.8)
     rb-inotify (0.9.7)
       ffi (>= 0.5.0)
+    rest-client (2.0.1)
+      http-cookie (>= 1.0.2, < 2.0)
+      mime-types (>= 1.16, < 4.0)
+      netrc (~> 0.8)
     sass (3.4.22)
     sass-rails (5.0.6)
       railties (>= 4.0.0, < 6)
       thread_safe (~> 0.1)
     uglifier (3.0.4)
       execjs (>= 0.3.0, < 3)
+    unf (0.1.4)
+      unf_ext
+    unf_ext (0.0.7.2)
     web-console (3.4.0)
       actionview (>= 5.0)
       activemodel (>= 5.0)
   jbuilder (~> 2.5)
   jquery-rails
   listen (~> 3.0.5)
+  mailgun_rails
   puma (~> 3.0)
   rails (~> 5.0.0, >= 5.0.0.1)
   sass-rails (~> 5.0)

app/mailers/application_mailer.rb

 class ApplicationMailer < ActionMailer::Base
-  default from: 'from@example.com'
+  default from: ENV['MAIL_FROM_ADDRESS']
   layout 'mailer'
 end

config/environments/development.rb

   # 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
+
+  config.action_mailer.delivery_method = :mailgun
+  config.action_mailer.mailgun_settings = {
+        api_key: ENV['MAILGUN_API_KEY'],
+        domain: ENV['MAILGUN_DOMAIN']
+  }
 end