title: Facing issue SocketError (getaddrinfo: Name or service not known) in spree
body: <p>Hello I have included given gem in my gemfile:</p>
  
  <pre><code>gem 'spree_mail_settings', github: 'spree-contrib/spree_mail_settings', branch: '3-0-stable'
  </code></pre>
  
  <p>and further done settings in spree-admin in configuration &lt; Mail method Settings
  <a href="https://i.stack.imgur.com/KpxTL.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KpxTL.png" alt="enter image description here"></a></p>
  
  <p>When I place order it gives me error </p>
  
  <blockquote>
    <p>2016-05-10T07:16:32.164733+00:00 app[web.1]: 
    2016-05-10T07:16:32.164734+00:00 app[web.1]: [ActiveJob]
    [ActionMailer::DeliveryJob] [9526835c-d5e7-4434-b716-a98b68b75da1]
    Performed ActionMailer::DeliveryJob from Inline(mailers) in 471.29ms
    2016-05-10T07:16:32.164735+00:00 app[web.1]: Completed 500 Internal
    Server Error in 1395ms (ActiveRecord: 179.9ms)
    2016-05-10T07:16:32.168574+00:00 app[web.1]: 
    2016-05-10T07:16:32.168583+00:00 app[web.1]: SocketError (getaddrinfo:
    Name or service not known): 2016-05-10T07:16:32.168583+00:00
    app[web.1]:   vendor/ruby-2.2.4/lib/ruby/2.2.0/net/smtp.rb:541:in
    <code>initialize' 2016-05-10T07:16:32.168584+00:00 app[web.1]:<br>
    vendor/ruby-2.2.4/lib/ruby/2.2.0/net/smtp.rb:541:in</code>open'
    2016-05-10T07:16:32.168584+00:00 app[web.1]:<br>
    vendor/ruby-2.2.4/lib/ruby/2.2.0/net/smtp.rb:541:in <code>tcp_socket'
    2016-05-10T07:16:32.168585+00:00 app[web.1]:<br>
    vendor/ruby-2.2.4/lib/ruby/2.2.0/net/smtp.rb:551:in</code>block in
    do_start' 2016-05-10T07:16:32.168585+00:00 app[web.1]:<br>
    vendor/ruby-2.2.4/lib/ruby/2.2.0/timeout.rb:88:in <code>block in timeout'
    2016-05-10T07:16:32.168586+00:00 app[web.1]:<br>
    vendor/ruby-2.2.4/lib/ruby/2.2.0/timeout.rb:98:in</code>call'
    2016-05-10T07:16:32.168586+00:00 app[web.1]:<br>
    vendor/ruby-2.2.4/lib/ruby/2.2.0/timeout.rb:98:in <code>timeout'
    2016-05-10T07:16:32.168587+00:00 app[web.1]:<br>
    vendor/ruby-2.2.4/lib/ruby/2.2.0/net/smtp.rb:550:in</code>do_start'
    2016-05-10T07:16:32.168587+00:00 app[web.1]:<br>
    vendor/ruby-2.2.4/lib/ruby/2.2.0/net/smtp.rb:520:in <code>start'
    2016-05-10T07:16:32.168587+00:00 app[web.1]:<br>
    vendor/bundle/ruby/2.2.0/gems/mail-2.6.4/lib/mail/network/delivery_methods/smtp.rb:113:in</code>deliver!' 2016-05-10T07:16:32.168588+00:00 app[web.1]:<br>
    vendor/bundle/ruby/2.2.0/bundler/gems/spree_mail_settings-d416a1e35589/lib/spree/core/mail_method.rb:8:in
    `deliver!' 2016-05-10T07:16:32.168588+00:00 app[web.1]:  </p>
  </blockquote>
  
  <p>Please guide me why I am facing this issue and what settings are required.</p>