In a business letter type the at least four blank lines below the complimentary close allowing room for the author to sign his or her name?

Certainly! In a business letter, after the complimentary close (such as "Sincerely" or "Best regards"), you should leave at least four blank lines to provide space for the author's signature. This space allows for a handwritten signature, which adds a personal touch to the correspondence. Following the blank lines, you can include the author's typed name and title if necessary.