title: NameError: uninitialized constant Mail::Parsers::ContentTransferEncodingParser
body: <p>Sometimes when I send mass email on heroku some of them fail with the following error:
  <code>NameError: uninitialized constant Mail::Parsers::ContentTransferEncodingParser
  </code></p>
  
  <p>I have no idea why is that but I think that maybe this maybe caused by using <code>attachments.inline in mailer</code>. Any ideas what may cause this problem?</p>