• Return receipt

In some programs, this feature will alert you when your email has been opened and read by the recipient. Most programs also let the recipient know that you've been notified. Be careful when you use this feature, because it might be interpreted as nagging (as in "I want to be sure you're reading my emails, you lazy so-and-so"). However, if you or your correspondent have been experiencing technical difficulties with sending or receiving emails, the return receipt feature offers a way to confirm that your message went through. This is also a useful feature when sending emails to extremely busy executives or people who travel frequently. If your message remains unread for several days, it's a good reminder for you to follow up with a phone call.