[JoshTriplett]

Style whatever you like however you like, but please do include a functional text/plain part in your multipart/alternative email, and please ensure it includes all the requisite information and links and URLs that the HTML version does.

I regularly encounter HTML email that has an empty text/plain part, or an error message, or a converted text version of an email that's missing the most critical information. For instance, I often get "confirm your registration/email" emails whose text/plain parts leave out the confirmation link or confirmation code.