Reasonable people can disagree about the "confronting" vs. "you'll only drive them together" schools of thought. But IF you're going to send an e-mail like that, then you have to back it up. What you've done is like telling your child "if you don't pick up those toys RIGHT NOW, you're not going to get any DESSERT!" ... and then, when they say "well, Dad, I picked SOME of them up, and I'm really TRYING here, but I'm just not sure I can pick ALL of them up..." you get into a big conversation with them about the pros and cons of picking up toys, then you hug, and tuck him into bed. Don't draw a boundary unless you intend to encorce it -- 100%. That's something I'm sure we ALL can agree on.