A memo has a heading consisting of four parts.
To: Name and position of the reader
From: Name and position of the writer
Subject: A phrase that focuses the reader's attention on the subject of the memo
Date: Date the memo is sent
Normally, the writer puts his initials next to his or her name as an official signature.
After the heading comes the body of the memo, the message being sent. The body of a memo will be organized according to the purpose of the memo. For instance, a progress report in memo form will usually be divided into a purpose statement, a work completed section, and a work scheduled section. An accident report will state the purpose, give a narrative and descriptive background discussion of the accident, and then discuss the investigation and findings.
Although the body is adapted to the purpose of the memo, we can still mention the overall structure of the body to any memo. Basically, a the body of the memo has two parts: the purpose statement and the explanation. Because the reader of the memo is often very busy, she is not likely to read the memo closely. Therefore, the first sentence should state the whole message of the memo in one sentence. This sentence is like an abstract to a report. One should not begin a memo with background information and work gradually to the main point. Instead the main point should come first and then the background and explanation of the message in fuller detail should follow. If the purpose of the memo is to ask someone to do something, that request should be in the first sentence. If the memo's purpose is to announce something, the gist of the announcement should be in the first sentence. If the purpose is to report something, the first sentence should summarize the report and the rest of the memo should elaborate.
One is often tempted to end the memo with a "cordially yours" and a signature, but these are not necessary and are usually excluded. When the message is complete, the memo is complete. Because memos are usually short, it is seldom necessary even to write a conclusion or summary; however, if the memo happens to be more than a page long, a summary may be in order.