While a simple "Hi," "Hello," or even "Hey" is appropriate in casual correspondence, a more formal salutation is appropriate when you are emailing about a business_related matter, such as a cover letter, letter of recommendation, or inquiry letter.
How to Write Business Letter: Suppose you are writing a business letter for the very first time. You will ask yourself the question ‘how to write a business letter’. There is no need to scratch your head. All Business letters follow a fixed format. The answer to the question how to write a business letter is broadly classified into four categories.