An indented letter style is a letter-writing style where the paragraphs are indented, and the date, closing and signature start at the center of the line. The paragraphs are typically indented by half an inch.
The indented letter format is not popular in modern business correspondence. Lynn Gaertner-Johnston of Syntax Training says that using the indented format can be an indication that the letter sender or the firm he is representing is traditional. However, she also warns that the format does not look elegant. For a modern and sophisticated appeal, she recommends the use of the full-block with no indention letter style.