Returning emails promptly is a great way to show someone respect. When you return an email right away, that person knows that they matter to you. This is a great thing to do with both work and home/personal emails.
So many times it is easy to read an email and say "I'll respond to that later" only to have a couple of days, if not weeks, go by before remembering to respond. A prompt response is always appreciated, but especially if the person writing asked you a question.
As you learn to respond more promptly to emails you will likely find yourself becoming more organized. You will get better at managing your time and handling problems and questions head-on, instead of waiting a day or two to think about them and respond. You will get more done and feel more accomplished!
Make a commitment to answer every email you receive within 24 hours of reading it. If possible, be prepared to respond to every email as soon as you open it. Read through the email and then reply immediately. Learn to read your emails in order of importance and you will respond quickly to the most important ones. Also, don't sit down to check your email unless you know you have enough time to respond to all the emails you've received. Perhaps try the tactic of not opening a new email unless the previous one has been answered.
This might not be possible for everyone. Some people receive hundreds of emails a day and have no way of answering each one personally and promptly. However, most email providers have an "auto-response" feature. Use this feature to your advantage--let people know that though you read every email that comes through you may not be able to respond right away. And if there is a better way to reach you (perhaps you prefer the phone?), let them know that, too. Make a commitment to answer at least 5-10 emails a day.
Some tips on how to manage your email.
Additional tips on how to properly manage your time on email.