In Salutation^x, Resume^x

Is it still current practice in business correspondence to use the words "Sir or Madam" when writing to a company? I presume that "Sir or Ms." is incorrect, but would like clarification. Thanks.

Guest wrote:How do i write the best cover letter job to a college or university department enquiring about a teaching position within their art department? I don not need student cover letter help, I need business cover letter for my career change cover letter. Should I fax cover letter example...