Whomever is not a stellar employee. She never answers her mail. She definitely doesn't make hiring decisions. Find out to whom you should address your letter. A good place to start is the company's human resources department.
Some companies accept only e-mailed resumes.
Others insist you personally drop off your paperwork. Whatever the rules, follow them. One trick is to get to know someone at the company. Join professional associations with the intention of meeting the right people. Ask friends or mentors to introduce you to folks.