Do you send more than a few dozen emails every day? Do you want to be more productive and save up to an hour a day? Recognize exactly what other people’s email in-box really is: a list of nouns.

Specifically, everyone you send messages to has an in-box that only tells them a few things and these two pieces of information are mission critical:

1. Sender
2. Subject

The first thing people do when they receive a message is to look at whom it’s from. Based on the relationship they have with you, they’ll respond right away, sooner or later -- or never. You can increase the likelihood that they’ll respond faster when you're making a request if you realize the power of the subject line.

Next read the subject line. Now, if you’re like most of the managers I advise, you probably keep this confined to a description of the email, focusing in on a noun or a phrase about a thing or things. But it can be more effective to include a verb near the start of the subject line. The most popular action words I’ve seen effectively used are the following:

Review
Confirm
Meet to discuss

Related: 5 Steps to Keeping Your Private Communications Secure

Look, don’t just read this article and wonder if this would work. Here’s an experiment to run: For the next 30 emails you send (about one day's worth of messaging for many of you), begin every subject line with the action that you need the recipient to take. 

As you write a message for the next 24 hours, spend an extra moment on each subject line.  The recipient's in-box is a giant list, right? Help that person out. Make it so that person can look down that list and see -- right in the subject line -- exactly what you would like the individual to do. My experience is that people respond faster, better and with more complete information.

Related: Creating a Responsive Email Design (Infographic)

After you run this experiment, return to your own in-box and look for how many replies you have from those 30 people you sent messages. Observe the response time and quality. Specifically, how long does it take for people to reply to you and how complete are their replies?

The subject line of an email may be the most important thing for you to optimize. Make those subject lines action oriented. Starting today consider how you can make the subject lines you write more valuable, relevant and helpful.

Related: Make It Stop! 5 Techniques for Managing the Email Onslaught.