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. When writing your business correspondence clearly state your purpose and connect your message directly to the items you are enclosing.13. Enclosures. An enclosure can prevent a letter from becoming too detailed. Add an enclosure notation after your signature at the end of the letter, and abbreviate it with "Enc." or "Encl. Leave out any unknown information. Filled out and forwarded to the TYCOM.