I've located the problem. HTML tags in the comment box throw an error. I'm working on a fix at the moment. For now, keep the emails plain text and they should work fine.
Recently the ammount of email I've been getting has dropped off significantly, and a few people have mentioned errors popping up when trying to submit from the talk section.
I've tested it myself, but I can't recreate the error, so if you could post more specific details of the error (error code maybe?) and what browser you are using etc... that would be helpful.
Thanks, I'll try to fix it as soon as possible.