Email As Cover Letter. You need to show the employer why you're a good fit for the position and to grab their attention so they look at your resume. A cover letter is rarely attached to resumes by job seekers.
Its purpose is to explain to the hiring manager how you found the job and why you're applying, as well as to briefly introduce you and your qualifications. Explain where you found the job posting or how you heard about the position. And remember to attach your resumé before sending.
Conclude with a subtle call to action to remind the hiring manager of the action you'd like.
You may also add some points that are already written in your resume, such as: skills, education and years of experience.
Writing about previous experiences if any is fruitful, and in the conclusion conclude by statements like, 'I look forward to hearing from you" etc. You don't need a mailing address, date, or signature. Cover letters shouldn't just carry your contact information, but also that of the company to which you're applying.