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The Mayfield Handbook of Technical & Scientific Writing
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Section 2.5


Use letters to communicate outside your organization. Whereas the memorandum is the primary vehicle for communication within an organization, letters are often used to communicate to individuals outside it, especially in formal and semiformal contexts.

Letters are an essential part of all business and technical communication because they are more formal and reliable than electronic mail and more precise and permanent than telephone or face-to-face conversations.

Types of Letters

Like memoranda, letters perform many functions in scientific and technical communication. The following are some of the most common types of letters written by people in technical fields.

Job application letters

Acceptance letters

Transmittal letters

Inquiry letters

Technical-information letters

Letters of recommendation

Format of a Letter

If your organization has a specific style for business letters, follow that format. Otherwise, follow the guidelines provided here.

Business letters are commonly either full-block formatted, with every line starting at the left margin and usually a business letterhead at the top of the page, or modified-block formatted, with the heading and the closing aligned at the center of the page.

Elements of a Letter

Business letters have the following elements:



Recipient's address




End notations


If you are using letterhead stationery, include only the date two lines below the bottom of the letterhead. Spell out the name of month.

If you are not using letterhead stationery, begin with your full address (city, street, and zip code) 1 to 1½ inches from the top of the page. Spell out address designations, such as Street, Avenue, and West. The state name may be abbreviated using the two-letter, all-capitals U.S. Postal Service designations. Include the date aligned at left with the address, spelling out the name of the month.

Recipient's Address

Two to four lines below the date, place the following items:

The recipient's address is always aligned on the left margin.


Place the salutation two lines below the recipient's address. The salutation begins with the word Dear, continues with the recipient's title and last name, and ends with a colon. If you are unsure of the recipient's gender and the recipient does not have a professional title, omit the title and, instead, use both the first and the last names in the salutation (Dear Leslie Perelman:). If you do not know the name of the recipient of the letter, refer to the department you are writing to (Dear Technical Support:). Avoid salutations such as Dear Sir or Madam:.


Start the letter two lines after the salutation. Body paragraphs should be single spaced with a double space between paragraphs. (Indenting the first line of each paragraph is acceptable but is more informal than the unindented style.)

Be concise, direct, and considerate. State the letter's purpose in the opening paragraph. Include supporting information in a middle paragraph or two, and conclude your letter with a brief paragraph that both establishes goodwill and expresses what needs to be done next.

If a letter requires more than one page, make sure there are at least two lines of body text on the final page. Never use an entire page for just the closing. The second page and all subsequent pages must include a heading with the recipient's name, the date, and the page number.

Closing Phrase

Write a complimentary closing phrase two lines below the final body paragraph. Yours truly, Sincerely, or Sincerely yours are common endings for professional letters. Capitalize the first letter of the first word of your complimentary closing, and end the complimentary closing with a comma.

Four lines below the closing phrase, write your full name. If you are writing in an official capacity that is not included in the stationery's letterhead, write your title on the next line. Your signature goes above your typed name.

End Notations

At the bottom of the last page of a business letter, end notations may show who typed the letter, whether any materials are enclosed with the letter, and who is receiving a copy of the letter.

The typist's initials, in lowercase letters, follow the initials of the author, in capital letters, and a colon or a front-slash (LCP:ecb or LCP/ecb).

An enclosure notation--Enclosure:, Encl., or Enc.--alerts the recipient that additional material (such as a résumé or a technical article) is included with the letter. You can either identify the enclosure or indicate how many pieces there are.

Enclosure: Article by I. W. Waitz

Encl. (2)

Enc. (2)

In addition to the enclosure notation, always refer to your enclosures explicitly within the text of the letter.

A copy notation (cc:) lets the recipient of the letter know who else is receiving a copy. Put each recipient of a copy on a separate line.

cc: Dr. Maria Lopez
Mr. William Astley

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