List courtesy copies at the very bottom of the letter following two lower case C's and a colon. This gesture informs the original recipient that others are receiving a copy of the same letter.
Courtesy copies were originally called carbon copies from when documents were written with a sheet of carbon paper placed between the original document and another sheet of paper, automatically producing a copy underneath. With the technological advances in digital communications, the term courtesy copy has become popular and more relevant with the use of email and word-processing. A courtesy copy provides for sharing information with more than one party.