The Hidden Costs of Ignoring Email Behind every unanswered email in your inbox is a somebody drawing unpleasant conclusions about you.

Today's working professionals are swimming in email -- it eats up a shocking 28 percent of our workweek. But that's not even the worst part. We often feel like such slaves to our inbox that we forget there are human beings on the other end.

Think of the last time you sent an important email and didn't get a response. Your first reaction was probably, He's just busy. After a few days, you wonder, Did he get my e-mail? A few days later, What did I do wrong? Then, invariably, What a jerk!

In recent years, it's become more and more "acceptable" to not respond promptly to e-mails, or worse, to not respond at all. Listen, I get it. We're all busy. But that's no excuse for bad behavior. Response time is a non-verbal cue that speaks volumes about who we are, for better or for worse.

There are valid reasons why don't respond. Terminally busy people usually have great intentions but fail in execution. It's a "too many emails, too little time" situation. They might see a message, plan to reply later, and forget. In fact, there is evidence that people with central roles in their team are less responsive simply because of the volume of messages they receive.

It might also be that we are complacent. Complacent people usually have some reason, conscious or unconscious, for their silence. At the benign end, they're worried about saying no or raising a difficult issue. At the extreme end, they're arrogant, self-absorbed, or brandishing their power. As one healthcare executive observed, "If they feel above you, they may feel unmotivated or that you don't "deserve' a response."

Related: If Your Cold Sales E-mail Didn't Get a Response, Make it Hot

If you think your benign neglect of email isn't hurting you, I hate to burst your bubble. This behavior could be holding you back more than you realize.

In one study, people who took two weeks to respond to an email, or didn't respond at all, were evaluated more harshly, assigned more negative intentions and viewed as less credible than their responsive counterparts. According to writer Margaret Heffernan, "How you deal with email says something fundamental about how reliable you are."

Put simply, if you don't respond, people won't trust you. When they don't trust you, they won't respect you. And when they don't respect you, they'll never see you as credible.

When there's no ready explanation for it, email silence has been shown to harm relationships. Shockingly, many will take it personally if you blatantly ignore their emails. They wonder, Do I not matter enough to warrant a reply?

I have a client who is a Fortune 500 C-level executive. Despite being tremendously busy, she's the most responsive person I know. Over her career, she's seen "smart talented people who have been derailed because they are just plain unreliable." She's found that when you're reliable, even if you're not always right, people will want you on their team.

I propose six steps for a responsiveness revolution.

1. Make responsiveness a priority.

Responsiveness starts with the right mindset. Accept the reality that your response time speaks volumes about your character. To get ahead in life, you can't ignore emails. And because most people are mildly to moderately guilty of this, they'll be pleasantly surprised by your timeliness.

2. Get organized.

I know someone who currently has 2,000 messages in his inbox. He leaves people hanging every day, despite being a kind and thoughtful person. It's impossible to be responsive without a time and an email management system. Whether you Take Back Your Life or focus on Inbox Zero, find a system that works for you and stick to it.

Related: Unleash the Full Power of the Email Auto-Reply

3. Pick a response window.

Being responsive is important, but you have to find a balance so you're not a slave to your email. Pick a window you can stick to. Because research has shown that 85 percent of responses are sent within 29 hours, I suggest that you reply to emails within one to two days. But if that's too aggressive, start with a target of three days. If you're consistent, people will know that you're trying and what to expect.

4. Acknowledge receipt.

As one executive recently told me, "Everyone's busy, but there's no excuse for not at least acknowledging a message. It takes five seconds." I couldn't agree more. If you send a response like, "Got your email. I'm tied up this week but will reply as soon as I can," most people will understand. You'll buy yourself goodwill and more time.

5. Say "no'' when you need to.

If someone asks you for something that you can't or won't do, for goodness sake, just tell them. Believing that "no response is the new no" is passive aggressive, cowardly and rude. Even if a stranger sends you an email, give them the professional courtesy of a reply, "Thank you so much for your request. I'm sorry that I can't help you." It will take you less than 15 seconds and they'll be out of limbo. As aptly noted in The New York Times, "Most of us can handle rejection. We can't handle not knowing."

6. If you fall off the wagon, apologize.

No one is perfect, and we all miss an email once in a while. If this happens, fess up: "Please forgive me for taking so long to respond." Don't offer excuses, just apologize and move on. After all, you're only human, and as long as you don't make it a habit, you'll keep their respect.

Above all, never forget that there's a human being on the other end of every e-mail. That person has their own deadlines, insecurities and stress. Just like you, they're probably doing the best they can.

I want to start a revolution of responsiveness. Let's make the world a better, more civil place, one email at a time. What do you say...will you join me?

Related: The 8-Second Challenge: Email Marketing for Our Shrinking Attention Span