Okay, I am going to be the odd one here. It really depends. Is this a personalized e-mail. Or is it something you are sending to a group of people? If it is a personalized e-mail, yes of course I will respond. If it is something that is going out to a group of people I will not. Two examples, if I talk to a friend on the phone and she tells me about an upcoming trip/surgery/event, and then sends out an e-mail to all of her friends informing them of the same thing, I feel no need to respond the e-mail. We spoke on the phone for two hours, I have nothing else to say. If the e-mail is from someone whom I worked on a project with two years ago and they send out an e-mail to everyone in their mailbox about their sister-in-laws husband cheating on her so she is moving in with them, I probably wouldn't respond to that e-mail. It was probably not really intended for me. Anything in between these two extremes, I would probably respond to, but to be honest it is on a case by case basis.