By Meghan M. Biro

People often wonder why they never hear anything back after they hit "send" on the email with a resume attached or on the online job application. If you're very lucky, you might have a preliminary email exchange with a recruiter and then never hear from them again. It's a depressing experience, and one that also casts a shadow on the hiring company's reputation. So why does it happen? Is it you, is it them, or is it just something every candidate must prepare for in the hiring process?

An oft-cited recruiter's complaint is that as many as 50% of people applying for a given job simply aren't qualified. Adding to the challenge, most large companies -- and many smaller ones -- use talent-management software to screen resumes, weeding out up to 50% of applicants before a human even looks at a resume or cover letter. The deck is definitely stacked against the job seeker. So how do you break through?

A woman with her head in her hands and elbows on a desk; a laptop is on the desk.

Image source: Getty Images.

Here are my top five reasons you're not hearing back after applying for a job, with five suggestions for ways to avoid the resume black hole.

1. You really aren't qualified. If a job description specifies a software developer with three to five years of experience and you're a recent graduate with one internship, it's unlikely you'll get a call. Avoid disappointment -- don't apply for jobs for which you lack qualifications. Most job descriptions are written with very specific requirements. Yes, the company is trying to find the most qualified candidate; yes, they are trying to weed people out. It's not personal, it's business.

2. You haven't keyword-optimized your resume or application. Job descriptions are salted with keywords specific to the skills or attributes the company seeks in applicants. A close read of the job description is a necessity, as is keyword-optimizing your resume and cover letter, if you're using one, or email. If the job description lists words in a certain order, e.g. a list of programming languages required, use the same order in your resume.

3. Your resume isn't formatted properly. You might think distinctive formatting will set your resume apart, but automated programs don't care if a document is pretty. Help a machine out. Be consistent in formatting – consider using separate lines for former employer, job title, and years worked.

4. Your resume is substantially different from your online profile. LinkedIn, Dice and other online profile sites can be useful tools, so it's important to make sure they match what's on your resume. This may seem to be a contradiction -- in No. 1, I advised keyword optimization -- but it's really common sense. Jobs worked, employers, years on the job and other details should match. The subtext here is always tell the truth.

5. The company received 500 resumes for one job posting, and yours was 499th in. Looking for a job is a job. Do your research -- know which companies you want to work for, organizations where you sense culture fit. Every morning, scour the job postings and jump on anything for which you're qualified (and in which you're interested). Being early with your resume or application does matter. Check back often in the first few days to make sure the listing hasn't changed. Often a company will post a job, and halfway through the process change the description.

It's hard to game the system. Your best bet is still a personal referral, and even that may not be enough to get a call. A guy I know gave his resume to a woman who worked at a company where a good job had been posted. He received an automated email noting his resume had been received but never heard another word. After a month he asked his friend to check with the recruiter. It turned out the job description had changed, but the recruiter never bothered to let the referring employee -- or the applicant -- know. This isn't unusual, unfortunately. So what can you do?

How You Can Get Noticed

1. Research interesting companies on social media. Find out who the recruiters are and follow them. Many will tweet new postings, so watch their streams and jump on anything for which you are qualified. And if they tweet news saying the company's had a great quarter, retweet the news with a positive comment.

2. Consider starting a blog in your area of interest or expertise. It's a social world; time to build a trail of breadcrumbs leading to you. Include the blog, and links to any especially relevant posts, in your emails to recruiters with whom you're working.

3. Get professional help with your resume. Either a resume writer or an SEO expert can help you increase your odds of getting through the talent management software. If you can't afford this step, read the top career blogs for advice.

4. If at all possible, don't wait until you're out of work to find your next job. I realize for many people this isn't possible or might even be offensive, but your chances of finding the next job are best when you're still employed.

5. Network. Old advice, but still true. Be visible, be upbeat, be informed about industry trends and news in your area of expertise.

Finding a job is tough, no question. I've talked to other recruiters who say they only respond to 30% of applicants. The odds are good you'll be in the more than 60% who hear nothing a lot of the time. Don't take it personally -- it's not a rejection of you, it's a reflection of the times. If you don't hear back, know you're not alone.

This article originally appeared on Glassdoor.com.