No, the author uses blank lines to separate paragraphs. Consider the parts or elements of a business letter. Notice that the first address indicated is the sender's. The dateline shows the date the letter was composed. I think the date is so important that it is a good idea to clearly designate it as a distinctive element by separating it from the sender's address.
Most writers choose a graphic from the selection provided by the software.
Others scan a photo or line art and bring this graphics file into a letterhead file. The letterhead file will also indicate the distinctive font and size of print of the sender's name and address information. You can easily copy this file and paste it into a new word-processing file each time you begin to write another letter. Then all you have to do is key in the rest of the document. This is the inside address, the name and address of the recipient of your letter.