title: Paperclip failed to upload msg file type
body: <p>I need to attach the msg file to rails, i have add the mime type for the msg filetype </p>
  
  <pre><code>validates_attachment :file, content_type: { content_type: ["image/jpg", "image/jpeg", "image/png", "image/gif", "application/pdf","application/vnd.ms-excel",     
           "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
           "application/msword",
           "application/vnd.ms-outlook", 
           "application/octet-stream",
           "application/vnd.openxmlformats-officedocument.wordprocessingml.document", 
           "text/plain"] }
  </code></pre>
  
  <p>but when upload with the sample msg file it went error </p>
  
  <pre><code>Command :: file -b --mime '/tmp/5e8ff9bf55ba3508199d22e984129be620170527-6239-gqgnhz.msg'
  Command :: file -b --mime '/tmp/5e8ff9bf55ba3508199d22e984129be620170527-6239-g903st.msg'
  (0.2ms)  ROLLBACK
  Completed 500 Internal Server Error in 26ms (ActiveRecord: 1.7ms)
  </code></pre>
  
  <p>any suggestion? i am using paperclip 5.1.0</p>