Dear Miriam,

I host a lot of Shabbat dinners for friends, and for a few recent meals, I've had guests cancel on me at the last minute. I've already made all the food, sometimes even set the table, and then I get an email that for some reason or other they can't make it. A last minute email is better than having people just not show up, which I've also had happen, but I can't imagine ever doing something this rude to a friend who's invited me for dinner. How should I respond when this happens, and is there any way to communicate to people before a meal that when they accept, I really expect them to show up?