I don't want to sound too negative, since I do like getting e-mail, but here are a few ground rules to keep you from wasting your time:

• Don't send me any suggestions or ideas for things Microsoft should do. I won't read them: I don't want to be accused of stealing your ideas, by you or by other people, and anyway Microsoft's lawyers would throw a fit if I did read them, regardless of what sorts of assurances you give me.
• If you are looking for a job, you can apply here. Please also e-mail me directly if you work in an area related to mine and apply for a job at Microsoft Research New England, but there's no point in e-mailing me regarding jobs in other parts of Microsoft.
• I can't help with admission to MIT. I can supervise graduate students in the Department of Mathematics, but the way that works is that you get admitted first and then find a thesis advisor, often after having been here a year or more. I'm happy to talk with current or admitted students, but talking with a potential advisor isn't necessary for admission and won't boost your chances. (Feel free to send questions, as long as you aren't thinking it will help you get admitted.)
• I won't solve your homework problems for you.
• I don't have the time to evaluate purported solutions to famous problems by authors without a convincing track record. Here is some advice.

I may be busy, so I make no promises to reply quickly. I'll try, though.