OK, I've put together a new repository on github[1]. I've modified the original code from Yesod to now include support for multipart/alternative, and to only create a multipart when there really are multiple parts. I've done some simple tests, and it seems to work just fine. Now a question for everyone interested in this library is: the API is currently very low-level. Should this package include higher-level wrappers? I'm sure people would love to see built-in support for serving over SMTP, but I think that's more appropriate for a different package. Proper SMTP support will also include SSL/TLS support, which will require even more dependencies. Another possible helper package (an idea from Jeremy Shaw) would be using Pandoc to automatically create multipart messages from markdown. Once again, I won't include support in the main package because it will increase dependencies. Anyway, I'd like to get a first version released within the week so it doesn't hold up Yesod 0.6, but the beauty of having it as a separate package is we can always make changes later. Michael [1] http://github.com/snoyberg/mime-mail