A friend asked me to review her resume this week. It was excellent. She then sent it to a prospective employer and bcc’d me. Despite a great resume, I doubt if she gets called for an interview since the cover letter contained at least three glaring typos.
Cover letters simply need to be short, to the point and typo free. No need to repeat everything in the resume. Just convey the key information–mention the specific job for which you are applying and one sentence about your relevant experience. Avoid subjective phrases like: “As you can see, I am perfectly qualified for this position.” Other examples of colossal cover letter mistakes are highlighted in Not Hired, an amusing blog produced by professionals who see a lot of bad resumes and cover letters.
By the way, I did inform my friend about the typos and she immediately sent a corrected cover letter and resume to the prospective employer with a Post-It note asking the recruiter to replace the earlier version with the revised one.