Did you get the e-mail I sent you yesterday? What about our lunch meeting tomorrow? Oh, and I’ll see you after class tonight.
The problem with that sentence and those questions is that today, yesterday and tonight do not refer to a specific date. That is a real problem if you opened your e-mail tomorrow and read that I wanted to meet with you today. Solution: add a date or at least the day of the week somewhere in the message when you use yesterday, today or tomorrow in an e-mail. See you tomorrow (March 4, 2010).