What Does CC Mean in Email? Carbon Copy Explained With Examples, Etiquette and Reply-All Rules

CC in email stands for "carbon copy". When you put an address in the Cc field, that person gets a copy of the message, and everyone else on the message can see that they were copied. The people in the To field are the ones expected to act or reply; the people in Cc are being kept informed. If you have ever wondered "what does cc mean in email", "what is an email cc" or "what is c c in email", that is the whole idea, and the rest of this guide shows how to use it well, how it works underneath, and where it goes wrong.

What does CC mean in email?

The term comes from the office world before computers. When a typist wanted a second copy of a letter, a sheet of carbon paper went between two pages, and the copy was literally a carbon copy. Business letters still end with a line such as "cc: Finance Team" to show who else received the letter. Email kept the habit and the name. In every mail program you will see three address boxes: To, Cc and Bcc.

In the technical standard for email messages, RFC 5322, "Cc" is a header field that carries a list of addresses. It sits in the message header next to "To" and "From", so it travels with the message and is shown to everyone who receives it. That is what separates Cc from Bcc, where the address is hidden. Our guide to what BCC means in email covers the hidden version.

CC vs To vs BCC

All three fields deliver the message. The difference is in what each recipient is expected to do and what they can see.

Most mail clients treat To and Cc the same way when you press Reply all: both groups receive your reply. The social difference matters more than the technical one. Being in To says "this is for you". Being in Cc says "you are in the loop".

When to use CC

• Keeping a manager or stakeholder informed. A project update goes to the client in To, and your manager is in Cc so they can see the thread without being asked to respond.
• Introducing two people. Put the person you are introducing in To and the new contact in Cc, or put both in To for a direct introduction, and say who they are in the first line.
• Creating a visible record. When you confirm an agreement or a deadline, copying the people involved shows that everyone saw the same wording.
• Looping in a colleague who will cover for you. Copy the person who will take over while you are away, so they have the history.
• Sharing with a team address. Copying a shared mailbox, such as a support or accounts address, keeps a copy where the team can find it.

When not to use CC

• For large lists of people who do not know each other. Every recipient sees every address. For that situation use individual messages or Bcc, and read our guide on when to use BCC.
• To apply pressure. Copying someone's manager on a first request tends to read as an accusation. Ask directly first.
• When the copy contains private details. Once an address is in Cc, that person receives the whole message and any earlier thread below it.
• For every message by habit. People who are copied on everything stop reading, and then miss the one message that matters.

How to CC someone in common email apps

The Cc field is hidden by default in several apps to keep the screen simple. The steps below show where to find it. Menus change between versions, so treat these as a guide.

1. Gmail on the web. Open a new message and click "Cc" at the right-hand end of the To line. A Cc row appears; type or pick the address.
2. Outlook. In a new message, select the "Cc" button next to the To box, or type addresses straight into the Cc row if it is already shown.
3. Apple Mail on a Mac. In a new message choose View, then Cc Address Field. A Cc row appears under To.
4. iPhone or iPad Mail. In a new message tap the "Cc/Bcc, From" row. It expands into separate Cc, Bcc and From rows.
5. Android Gmail app. Tap the small arrow next to the To field to reveal the Cc and Bcc rows.

CC etiquette and the reply-all problem

The biggest practical risk with Cc is not the field itself. It is Reply all. When a message with twenty people on it gets a "Thanks!" from each of them, nineteen people receive eighteen pointless messages. A few habits prevent most of the trouble.

• Reply to the sender only, unless everyone needs your answer.
• Before pressing Reply all, look at the recipient list. If it is long, ask whether all of them need this.
• When you want to remove someone from a thread, say so: "Moving Sam to Bcc to spare their inbox." Many people prefer a note to silently dropping someone.
• If you are copied and have nothing to add, do not reply. Silence is the correct response to Cc.
• State the action at the top. "For your information, no action needed" in the first line tells a Cc recipient they can stop reading.

What other things does "cc" mean?

People who search for "in mail what is cc" are almost always asking about carbon copy. The same two letters turn up elsewhere, which is why the search results can look odd. In a printed letter, "cc:" at the bottom lists who else received it. In everyday speech "I'll cc you" means "I will copy you on the message". In payments, "CC" often means credit card. In web forms "CC" may mean the card verification field. In code and email APIs, "cc" is the name of the parameter that lists the carbon copy recipients, which the next section covers.

How CC works behind the scenes

Email delivery has two layers, and Cc lives in only one of them. The envelope is the set of instructions that mail servers use to deliver the message. In SMTP it is made of the MAIL FROM command and one RCPT TO command per recipient, as RFC 5321 describes. The message is the headers and body that the recipient's mail program shows, including the To, Cc and Subject lines.

The mail server delivers to every address in the envelope. The Cc header is only a label inside the message, so the recipient's app can show who else received it. That is why a Cc address must appear in both places when you send programmatically: once in the header so it is displayed, and once as a recipient in the envelope so the server actually delivers to it. A common mistake is to set the Cc header and forget the envelope list. The header then shows a name, but that person never gets a copy.

import smtplib
from email.message import EmailMessage

msg = EmailMessage()
msg["From"] = "orders@example.com"
msg["To"] = "customer@example.net"
msg["Cc"] = "accounts@example.com"
msg["Subject"] = "Your invoice"
msg.set_content("Your invoice is attached to this order.")

# the envelope lists every recipient, including the Cc address
with smtplib.SMTP("smtp.example.com", 587) as s:
    s.starttls()
    s.login("SMTP_USER", "SMTP_PASSWORD")
    s.send_message(msg)   # send_message reads To, Cc and Bcc from the headers

The host name, user and password above are placeholders. Take the real values from your dashboard, and read our guide to SMTP settings, ports and authentication for the connection details. In many email APIs the same idea is a "cc" field next to "to". Check your provider's reference for the exact name.

CC for people who send email at scale

If you send transactional or marketing email from an application, a few Cc habits are worth knowing.

• Do not copy customers on each other's messages. Putting several customers in To or Cc exposes their addresses to each other, which is a privacy problem. Send one message per customer.
• Copy internal teams deliberately. Sending a copy of every order confirmation to an accounts mailbox is fine. Do it with a Cc or Bcc to a controlled internal address, and make sure that mailbox can handle the volume.
• Each added recipient is another delivery. Every address is checked separately by the receiving servers, and a bad address can produce its own bounce. Keep your lists clean, as we explain in email deliverability metrics: what to measure.
• Do not change headers after signing. If a header covered by your DKIM signature, such as Cc, is changed after the message is signed, the signature fails. Set all recipients before signing. Our DKIM setup guide explains what is signed.
• Authenticate the sending domain. Copies of a message are still judged on the sender's reputation. Set up SPF, DKIM and DMARC first.

Quick answers to common questions

• Can the person in Cc reply? Yes. They can reply to the sender only, or to everyone.
• Does Cc show in the recipient's inbox list? No. The inbox shows the sender and subject. The Cc line appears when the message is opened.
• Is Cc legally different from To? Not in how it is delivered. Both are normal recipients. Your organisation may have its own rules for who must be copied on certain messages.

References and further reading

• RFC 5322: Internet Message Format
• RFC 5321: Simple Mail Transfer Protocol
• RFC 6376: DomainKeys Identified Mail (DKIM) Signatures