However, if your letter is completed over a number of days, use the date it was finished in the date line. The date line is used to indicate the date the letter was written. Include only the street address, city, and zip code. Do not write the sender's name or title, as it is included in the letter's closing. If you are not using letterhead, include the sender's address at the top of the letter one line above the date. The sender's address usually is included in letterhead. This resource is organized in the order in which you should write a business letter, starting with the sender's address if the letter is not written on letterhead. Download the free Acrobat Reader Parts of a Business Letter This resource is enhanced by an Acrobat PDF file. Media File: Writing the Basic Business Letter Writing Letters of Recommendation for Students.