It may seem like a code, and in some ways it is, but the CC on a letter is a way to acknowledge someone while keeping the focus on the receiver of the letter. It directs those who are reading your letter to who it is intended to be sent to as well as who is involved in the message. It keeps all involved in the loop, so to speak. There are a few ways to go about including people on a CC, once you truly understand what a CC is meant to convey.
The CC field at the end of a letter or at the beginning of an email under the "To" heading is a throwback to business letter writing in the age of carbon machines. Carbon tissue paper was placed behind sheets of plain paper or letterhead and all that was typed on the plain paper went through to the copy. The carbon copy looked like a replica of the original aside from its paper and ink formats. The CC was placed at the bottom of the letter to inform who was receiving the missive other than the original. It was meant to create a paper trail of sorts. It helped the typist understand how many copies needed to be created and who was to get each copy that was typed under the original.
Why Include a CC
It is intended to have the receiver of the original email understand that other people are being informed of the subject matter of the email. It is often used when two parties need to discuss action, trade contact information or settle on an agreement. The third party, or CC bearer, is therefore put into the loop, so they don’t have to send a follow=up email or question if the matter has been dealt with by the other parties.
How to Address a CC on a Letter
Other than the formalities of including the contact information of the CC person so that they will receive all the needed information, there isn’t much more to do to be formal. In a typed letter, the CC goes at the bottom left corner of the original letter. A CC in modern missives is usually in the form of an email. In that case it would be under the To heading and before the BCC line. If you intend to bring the person into the conversation in the letter, doing so in the second paragraph to refer back to why the missive is being sent should suffice.