Whether you're typing a business letter that you will e-mail to someone or snail-mail, if you intend to attach documents to your e-mail message or enclose additional materials in your envelope, it's proper business etiquette to indicate at the bottom of your letter that you're attaching documents or enclosing additional pages that are not part of the letter itself. A professionally crafted business letter that indicates the presence of enclosures will let the recipient know what should be included with the letter.
Scroll down to your signature on your letter, or to the last line of your address, if you included it below your signature.
Press the “Enter” key on your keyboard several times to add two or three line spaces beneath your signature or address.
Type “Enclosure” if you're including a single enclosure or attachment or “Enclosures” if you have more than one. If you have multiple ones, you have the option of stating the number in parentheses -- for example, Enclosures (2).