One nail-biting aspect about email is that you’re never sure if the person you sent your message to has actually opened it and read it. This is especially the case if it’s an important message. When you don’t hear back as quickly as you’d like, you then begin to doubt if the message was ever even received, which could lead to unnecessarily contacting them by different means. This only looks desperate. To calm your nerves, there’s an extension for Chrome that tracks details like this for Gmail.