If you are addressing a company for the attention of someone what is the salutation - is it dear sirs?

If you know the name or the job title of the individual you may use that as your opening. However if you do not have any information you should address it to "To Whom It May Concern" Unless you know specifically the name of the person you are addressing, it is probably most correct to say Dear Sir or Madam. If you addressing the corporation as a whole, you might want to say Dear [Company Title]. But if not, Dear Sir or Madam is appropriate because it definitely addresses whatever gender your reader is.