Contrary to what you’ve heard or read, cover letters are still important today. They’re not necessarily essential or required in every industry or for every role, but savvy job seekers always have one ready to go.

“A lot of companies still ask candidates for a cover letter when they apply, especially if they’re doing so through an online application system,” says Tina Nicolai, executive career coach and founder of Résumé Writers’ Ink. “And while it might seem annoying to have to write one, it’s actually beneficial to you, the candidate, to provide one—as long as it’s well-written and free of errors.”

She says the cover letter is the best place to show you’d be a great cultural fit by letting your personality come through; to prove that you’re credible by using metrics that detail your achievements; and to connect with the hiring manager by sharing a bit of unique information about your past, your competencies, and your character.

She also highlights a few things you should never do in your cover letter.

“These are common mistakes I see all the time,” Nicolai says. “If you want your cover letter to help you, not hurt you, you’ll want to avoid these errors.”

1. Typos and grammatical errors. 

Typos are a really easy way to land your application in the “no” pile.

Your communication skills are perceived according to how well the letter is written. If a typo or grammatical error is present, the reader may think you were ‘too busy’ or lazy to check your work or don’t care enough about this job to take the application process seriously. Or worse, they’ll think you just don’t know how to spell.”

Never rely on spell check. Ask a friend or family member to look it over before you submit the cover letter to the employer.

2. Writing too much.

Today, gatekeepers (recruiters and hiring manager) do not have the resources or time to read each candidate’s resume and multi-page cover letter. Stick to one page. And because people have short attention spans today, and less time to read each cover letter in full, I suggest writing in bite-sized nuggets or bullet points.

3. Addressing the letter to the wrong person. 

There’s absolutely no excuse for addressing your cover letter to the wrong person. If no name is provided, omit it completely and list your name and targeted position.

4. Not tailoring the cover letter to the company or job you’re applying to. 

The hiring manager will know if you’re using a generic, “one size fits all” cover letter. And they won’t be impressed. Customize each cover letter targeting the specified job description. A master cover letter is fine to use as a template or outline, but always remember to tailor it.

5. Forgetting to replace a company name or job title. 

If you’re applying for job after job and tailoring your cover letter to each one (like you should be!) you may find yourself replacing words, names, and titles—rather than rewriting your cover letter from scratch over and over again—to save time. But be very careful when you do this. If you forget to replace the company name or job title, this will be a huge turn off to the employer you send it to.

6. Being too humble.

“Some candidates may think full disclosure is to be commended when in fact it can work against the person. For instance, saying something like, ‘While I don’t possess 15 years in leadership, I have led teams and filled in for supervisors when on vacation,’ won’t impress.”

Talk up what you have achieved and do so with confidence. For example, something like this might work better: “I have led teams for 15 years throughout many phases in my current company. With each leadership experience, I gained XYZ."

7. Being too confident.  

While you don’t want to be too humble, you also don’t want to come off as egotistical. It can be easy or tempting to go overboard boasting about how smart or talented you are in your cover letter,But don’t. Instead, stay focused on your fact-based achievements and tone it down on the superlatives. Motivate with a balanced approach, and let the reader figure out on their own just how fabulous you really are.

8. Lying

This is pretty obvious—but don’t fib. Ever. It doesn’t help anyone, and they will find out eventually.

9. Justifying why you were part of a layoff or why you quit your job.  

Candidates need to focus on the here and now. Employer want current information, succinctly. Why you were laid off or why you quit isn’t important. This becomes an immediate red flag and the perception of the hiring manager tends to be, this person isn’t quite ready to move forward’ or ’there are a lot of issues that are unresolved, and those aren’t the messages you want to send.

10. Listing references.

Save the references for the end of the process. The cover letter is no place to start listing references or snippets from your latest review.