How to address graduate school recommendation letter? Since I'm applying for grad school, I'm currently in the process of acquiring recommendation letters from my professors. They usually ask me a few questions about how to guide the letter, such as what do I want to emphasize and how to address the letter?

How does one address a grad school applicant's recommendation letter? I mostly settle for "Dear Madam or Sir". Is "Dear Graduate Admissions Committee" or some other alternative considered better?
According to Wikipedia


Dear Sir or Madam or 'Sir/Madam' (If the gender of the reader is unknown).
To Whom It May Concern (If the writer wishes to exclude the gender of the reader from the salutation and/or to convey that the reader should forward the copy to one more suited to receive or respond appropriately).


As @Davidmh has mentioned it is least concerned. I personally have chosen to use "To Whom It May Concern" when I applied to grad school as in some grad schools the recommendation letters might get forwarded from the admissions staff to various professors. 

Edit : The first is British English and the second is American English as mentioned by @Davidmh