I played with the webmail package in December, and it's not great, but it's not too bad either. With some guidance, he or another student or novice could probably make it a lot better.
I made some improvements to webmail, and I should probably stick the result in CVS under contrib.
I don't know if ns_imap is production-quality, but it was pretty simple to work with, and it worked for me to check my mail.
I undoubtedly think, however, that using IMAP is the way to go. We don't want to make our own mail storage in the DB, the way Jin did with the old webmail package. Let an IMAP server deal with that, and we'll just integrate with that IMAP server. Everybody already has an IMAP server anyway.
Then if you want to reuse an email as a knowledge object, say, we could just offer a "post to KM" link, which would copy the content. The same thing could be done with forums and other content, for that matter.
/Lars