I'm using MimeMail 6.x-1.x-dev, with Simplenews 6.x-1.0-rc6 Mail is delivered as plain text, with attached html file, when we send through MS Exchange using Outlook. A POP3 account works fine with Outlook. Anyone familiar with, or know a way to fix this? There are posts that skirt this issue on drupal.org; but no clear solutions (as far as we can tell): MimeMail not sending HTML, but does so when CSS Combiner is enabled. http://drupal.org/node/422424 MIME Mail send plain text format http://drupal.org/node/312182