When should "cc" be used in correspondence?

Using "cc" in correspondence is primarily intended to indicate the other recipients who will receive a copy of the message along with the primary addressee. This practice is vital for ensuring transparency and keeping relevant parties informed about the communication. When "cc" is used, it signifies to all recipients that the message is being shared with others, which can help maintain clarity and ensure that everyone who needs to be in the loop is informed.

In contrast, the other options pertain to different functions of correspondence. For instance, labeling information as confidential is done through specific terms and phrasing, rather than using "cc." Emphasizing importance typically involves formatting or language choices, rather than the "cc" notation. Lastly, while filing purposes may involve retaining copies, that function is not the primary purpose of the "cc" designation, which focuses on notifying multiple recipients rather than filing protocols.