Cover letters are debatable. Many people think that they are no longer necessary, while others are convinced that you must send one with every job application. The truth is somewhere in the middle. While there is a very good chance that no one is going to read your cover letter, not sending one can still hurt your chances of getting the job.

Here’s why.

The majority of HR professionals and recruiters that I have spoken with over the years say that they seldom if ever read cover letters.

In the days of mailing or faxing in your resume to apply for jobs, it was natural to include a cover letter expressing your interest in the position and explaining how the accompanying resume makes you a good fit for it. You could be fairly confident that those letters would be read by the hiring manager.

However, these days, most job postings receive hundreds of applications, and employers don’t have the time to read hundreds of letters. Most skip right to the resume. If the applicant seems to have the qualifications and looks like a good fit for the role, they’ll get put aside for a potential interview. If the resume lists credentials and experience that don’t seem to fit the job, the candidate won’t make the cut.

In either case, the employer came to the decision without ever reading any accompanying cover letter.

The trouble is that many people write one polished and professional generic resume that highlights their skills, experience, and accomplishments, and they sent this to every job they apply for. They use their cover letter to express their interest in the specific job and to bridge the gap in any career shift from past jobs to the potential new one.

The cover letter is the only part of the application that is tailored specifically to the targeted employer and expresses the candidate’s knowledge and interest in that particular company.

In that scenario, the busy employer receiving so many applications that they don’t have time to read letters only sees your generic, untailored, possible unrelated resume and not your introduction letter that explains how you’d be great for that role. Generic resumes are a dime a dozen and they get quickly rejected. Counting on your cover letter is a career-limiting move. Your resume itself has to be customized for each job that you apply to – highlighting your core credentials that are most relevant for that specific job.

You might think that since you’ve customized your resume for the job, and most employers don’t read cover letters anyway, that you needn’t bother writing one. Don’t make that mistake.

Why? Because a potential employer might want to read it.

Some hiring managers still read the cover letters of each candidate who applies for their jobs, while others will go back and read just the cover letters of applicants they’ve shortlisted for further consideration.

In either case, if your potential employer wants to see a cover letter and you haven’t sent one, that’s a mark against you. Do you really want to come across as the candidate who put less effort into your application than others?

A smart cover letter introduces yourself and your interest in the job and explains how you would be a great fit for it.

However, your resume has to do this too – without simply restating what’s in the cover letter. Because while the resume must stand alone, both documents might be read. And you don’t want the employer to be reading the exact same message twice.

You increase the success level of your job applications by putting full effort into making each one as relevant as possible to the job you’re targeting. This means customizing your resume every time and writing a professional cover letter. (Just don’t count on anyone reading it.)