A business letter is easily recognizable by its format and style. There are three formats for laying out a business letter and several integral parts that make it uniquely a business letter. You can use the business-letter format in any professional communication.
Format
The layout formats for business letters are block, modified block and semi-block. In block format, the entire letter is left-justified and single-spaced, except between paragraphs, where there is a double space. In modified block, the letter's body is left-justified and single-spaced, with the date and closing tabbed. In the semi-block format, the paragraphs in the body are indented and the rest of the letter is left-justified.
Font and Punctuation
Times New Roman, size 12, is the generally accepted font for business letters because of its readability; Arial is used occasionally as well. If you choose not to go with either of these common font styles, make sure that the one you choose is easily readable. Use a colon after the salutation, not a comma. Use a comma after the closing.
Date
Make sure you have the correct date format for your recipient. If writing to American companies, use the month/day/year format (August 13, 2009), and if writing to a non-American company, use the day/month/year format (13 August, 2009). Put the date 2 inches from the top of the page. If it has taken multiple days to write the letter, use the date the letter was completed.
Addresses
If you include the sender's address, put it one line below the date, without the sender's name or title. The sender's address also can be placed after the closing. The recipient's address (also referred to as the inside address) should go one line below the sender's address or one line below the date if the sender's address is at the bottom of the letter or not included. The recipient's name and personal title should be used, and the postal address goes directly below the name. The addresses should be left-justified.
Salutation
For the salutation, write the name the same way as in the inside address, with title and both given and surname written out. If you are unsure of the person's gender, using the person's full name is acceptable.
Closing
The closing should go one line after the last paragraph of the body. Capitalize the first word only, and follow it with a comma. Leave four lines between the closing and the sender's name for the sender's signature.
Enclosures
If documents or other media will accompany the letter, add the word "Enclosures" one line below the sender's name in the closing. You also may list the various enclosures. If someone else typed the letter for you, add her initials below the closing or enclosures.