title: Hide text/plain from user in SMTP
body: <p>To solve a problem where <a href="https://stackoverflow.com/questions/10873269/correct-email-format-for-email-with-plain-html-and-an-attachment-in-smtp/10899430#10899430">SMTP servers won't display attachments with emails that have content-type set to multipart/alternative</a>, I've had to set the email to multipart/mixed, but this has the unfortunate side-effect of displaying both the plain text and the HTML, which create pointless duplication and is unsightly to the user.</p>
  
  <p>With multipart/mixed set, is there any way to hide 'text/plain' (without removing it as it's going to be used by a parser) from the user and just display the HTML? I am referring only to hiding it for cilent programs (such as hotmail, yahoo, etc) and not IMAP etc where the user can see everything.</p>