The Reply function offers many advantages over creating a new e-mail. First, it’s easier. You don’t have to retype the sender’s address (which also means you can’t mess is up). Second, it allows you to easily include the previous communication, so you can read and respond to the entire conversation in a single e-mail. Third, using the Reply function ensures that all of the follow-up e-mails have the same subject, making it easier to sort and review the entire conversation later.