A Cover Letter to your CV ought to carry soul of your CV. It is a short teaser, that excites the reader about your profile. In fact, it can be a piece of art, that beautifully, and using the full force of narrational English, showcases your background, skills and motivation in applying for a job. It can engage the recruiter better than any formatted CV attempts to. Can be used as the email advancing your CV. The subject line suggested for the email also carries punch.