If the letter you are writing is a personal one, do include a salutation (Dear Mr. Deepson, Dear Ms. Mary, etc.).
If the letter is a general one, say “To Whom it May Concern” or simply avoid a salutation.
This paragraph tells your connection with the person for whom you are writing the recommendation letter. Include how you know the person and why you are qualified to write the letter.
It contains the specific information relating to the person for whom you are writing the letter. It should include why they are qualified, what they can contribute, and why you are writing the letter.
If it is a specific letter with reference to a candidate for a particular job opening, try to include information on how the person’s skills match the position they are applying for.
This of the letter contains a brief summary of why are you are recommending the person.