When I was 20 I saw a job listing in the local paper. (Remember those?) A small radio station was looking for a weekend DJ. Though my radio experience to that point consisted of struggling through one news break for my college radio station, I applied.

I even got an interview. Sweet. I sent a follow-up note. I waited to hear back.

And I waited.

And I waited.

And I never heard back.

And while you might be thinking, "Who cares?" here's the thing: Thirty-five years later, I haven't forgotten, not that I didn't get the job, especially since I wasn't qualified, but that I never heard back.

That part still pisses me off.

We've all hired people we just knew would be superstars who turned out to be duds. And we've all passed on people who turned out to be superstars at another company. (If you're like me, you regret the ones you let get away more than the ones you had to let go.)

Those are big mistakes, but they pale in comparison to this:

Failing to follow up with and provide closure to every person who applies for a job.

Unfortunately, it's a mistake most companies make. John Younger, the founder of Accolo, says their research shows that over 90 percent of companies fail to provide closure to candidates who apply. "And," he says, "we've yet to meet a job seeker, hiring manager, recruiter, or company who feels that figure is off."

So why is failing to follow up with job seekers such a major mistake?

1. Failing to follow up is incredibly rude.

Say you pay me a compliment and instead of saying "Thank you," I turn and walk away. You'd be a little pissed, right?

So why, when a person pays your business the highest compliment of all--saying they would like to work for you and therefore spend more time with you than they do with their family--is it acceptable for you to ignore them and never respond?

2. Failing to follow up hurts your business.

A friend of John's is the COO for a global retailer with over 100,000 employees. When he spoke to a person who had applied for a job at one of the retailer's locations, she said she was so upset by the way she was ignored that she would never shop there again.

"The company received approximately 3.5 million job applications a year," John says. "By not providing closure, how many customers -- some of them huge fans of the brand, since most people want to work for a company they like -- did they lose?"

The same principle extends to a small business in a small town. Say I apply for a job at your company. I'm excited. I'm hopeful. I want to work for you. I tell my friends I applied.

You don't respond. I'm in limbo until, eventually, I realize you never will.

My friends ask how it turned out. I tell them I never heard from you--not even a perfunctory "Thanks, but no thanks."

What happens then to the way people perceive your company? Of course you'll never know, because unlike customers who have a problem with your products or services, I won't complain. My friends won't complain.

We won't complain to you, but I promise we'll complain about you.

3. Following up is the right thing to do, and you should always try to do the right thing.

Before you post your next opening, determine how you will close the loop with everyone who responds or applies.

Maybe you'll use an automated hiring and notification system. Maybe you'll do it manually. How you close the loop doesn't matter, as long as you are unfailingly prompt, courteous, and respectful. Deciding which tools or processes to use isn't as important as deciding that you will always respond to every single person who wants to work for you.

They've hung themselves out there, professionally and emotionally, by applying--so never leave them hanging.

Besides the fact it's the right thing to do, don't forget that if you do leave them hanging, like me, they will never forget.