I have learned a few things after that though:
- text files can also be included as Strings, not just as InputStreams
- a Multipart with MIME type "multipart/alternative" is used for a body that has both a plain text and an HTML part
Email is the wrong medium for HTML forms - that's what web servers (or servlet containers) are for.
Furthermore -as a bit of advice- never send emails that only contain HTML: there are just too many clients that don't support it, and users that sufficiently dislike it to turn HTML support off in their clients.