In this article, we explain what an enclosure is and how to cite one, and we provide an example of an enclosure in a business letter. State a Clear Purpose.When writing your business correspondence clearly state your purpose and connect your message directly to the items you are enclosing. Window envelopes eliminate the cost of addressing envelopes and the risk of putting letters in the wrong envelopes. To format letters for use with window. The following pages are suggested letter templates for Zoning Applicants. Add an enclosure notation after your signature at the end of the letter, and abbreviate it with "Enc." or "Encl. Letter from John Adams to Abigail Adams, 3 April 1797, with enclosure. 6 UNIT Unit 6 87 Correspondence LESSON 26 Business Letters LESSON 27 Business Letters With Enclosure Notations LESSON. Perhaps because enclosure letters are so mundane, they have often been a target for the use of stilted and somewhat absurd lan- guage.