What Does BCC Mean in Email? Blind Carbon Copy Explained, When to Use It and When Not To

BCC in email means "blind carbon copy". Addresses in the Bcc field receive the message, but their addresses are hidden from every other recipient. The people in To and Cc cannot see who was blind copied, and the blind copied people do not appear in the headers those recipients receive. If you searched for "bcc meaning in email", the short version is: Bcc is a private copy. This guide explains how it works, when it is the right tool, why it is the wrong tool for bulk mailing, and what to do instead.

What does BCC mean in email?

BCC extends the idea of the carbon copy (Cc). With Cc, everyone on the message can see who else received it. With Bcc, the word "blind" means the other recipients are blind to that address. The message arrives in the Bcc recipient's inbox as normal, but nothing in the copies that the To and Cc recipients get reveals that a Bcc copy was sent.

The Bcc header is defined in RFC 5322, the standard for the format of email messages. The standard allows a message to omit Bcc entirely, or to carry it with the addresses removed. In practice every mail program strips the addresses before the message leaves your server, so the hidden copy stays hidden.

BCC vs CC vs To

When BCC is the right choice

• Protecting the privacy of recipients who do not know each other. A small group, such as the parents of a school class or the guests of an event, often should not see each other's addresses. Putting everyone in Bcc keeps addresses private.
• Moving someone out of a busy thread. When a person has served their purpose in a long exchange, you can say "moving you to Bcc to spare your inbox" and then send your reply with them in Bcc. They stop receiving the later replies unless they are copied again.
• Keeping an internal record. Many teams Bcc a shared mailbox, for example a CRM address or an archive address, so that a copy of each outgoing message is stored without showing the address to the customer.
• Introductions. When you introduce two people and want to take yourself out of the follow-up, move yourself to Bcc in your note so replies go to the two of them.
• Compliance copies. Some organisations must keep a copy of certain messages. A Bcc to a controlled archive address meets that need without cluttering the message.

When BCC is the wrong choice

• Secretly copying a boss to catch someone out. It tends to backfire, because a Bcc recipient who presses Reply all exposes themselves to everyone.
• Sending marketing or newsletters. This is the most common misuse, and the next section explains why it hurts.
• Sensitive messages. Bcc hides an address from other recipients. It does not encrypt the message or stop the Bcc recipient from forwarding it.
• Hiding a conflict of interest. If a copy would matter to the main recipient, copy openly.

The reply-all risk for Bcc recipients

When you are a Bcc recipient, you can see the To and Cc addresses but nobody can see yours. If you press Reply all, your reply goes to everyone you can see, and your address appears as the sender. That tells everyone you were blind copied. Reply to the sender only, or write a fresh message, unless the group should know you were included.

How BCC works behind the scenes

Email delivery uses an envelope and a message. The envelope is the list of recipients given to the server with RCPT TO commands (RFC 5321). The message is the header and body that the recipient reads. A Bcc address goes into the envelope so the server delivers to it, but it is left out of the headers, or the header is removed, so nobody else sees it.

The details differ by program. Some mail programs send one copy to all recipients and strip the Bcc header. Others send a separate message to each Bcc recipient. Either way, the Bcc address is added to the envelope and kept out of the visible header lines. The sender's own sent copy usually still shows the Bcc list, which is why the sender can see who was blind copied.

import smtplib
from email.message import EmailMessage

msg = EmailMessage()
msg["From"] = "support@example.com"
msg["To"] = "customer@example.net"
msg["Subject"] = "Re: your question"
msg.set_content("Thanks for getting in touch. Here is the answer.")

archive = "archive@example.com"          # the blind copy
with smtplib.SMTP("smtp.example.com", 587) as s:
    s.starttls()
    s.login("SMTP_USER", "SMTP_PASSWORD")
    # the Bcc address is in the envelope but not in the message headers
    s.send_message(msg, to_addrs=[msg["To"], archive])

The host name, user and password are placeholders. Use the values from your own dashboard and read SMTP settings, ports and authentication for the connection settings. In an email API the same thing is usually a "bcc" parameter. Our guide on choosing between SMTP and an API explains how the two approaches handle recipients.

Why BCC is a poor tool for bulk email

Many people start newsletters or announcements by putting everyone in Bcc. It works for ten people. At a few hundred, it causes real problems.

• One message, one fate. A single message with hundreds of recipients is judged once by each receiving server. If it is flagged as spam, the whole batch is affected at the same time.
• Limits. Mail providers cap the number of recipients per message and per day. Hitting a limit can stop a send halfway through, and you may not know who received it.
• No personalisation. Nobody can be greeted by name, and the To line often has to be your own address, which looks odd to recipients and to filters.
• No unsubscribe handling or tracking. Bulk senders need working unsubscribe links, bounce handling and complaint monitoring. A Bcc blast gives you none of that.
• Risk of exposure. One slip, such as putting the list in To or Cc by mistake, publishes every address at once. Such incidents are a classic data-protection problem.
• Reputation damage. Mixed lists with old or invalid addresses cause bounces that count against the sending address or domain.

BCC and deliverability

For a sender, the visible recipients and the hidden ones are all deliveries that receiving servers must accept. Filters look at the sender's reputation, the content and the authentication, not at which field an address was in. Before you send any message to a group, make sure the sending domain is authenticated with SPF, DKIM and DMARC. If messages land in spam, work through our spam troubleshooting checklist.

How to BCC someone in common email apps

1. Gmail. Open a new message and click "Bcc" at the right of the To line. A Bcc row appears.
2. Outlook. In a new message open the Options tab and choose Bcc to show the row. In some versions it is on the message itself.
3. Apple Mail on a Mac. Choose View, then Bcc Address Field.
4. iPhone or iPad Mail. Tap the "Cc/Bcc, From" row so that the Bcc row opens.
5. Android Gmail app. Tap the arrow next to To to reveal Cc and Bcc.

Frequently confused points

• Can the To recipient tell I used BCC? Not from the headers they receive. They may notice if a Bcc recipient replies to everyone.
• Does BCC count as a recipient? Yes, for delivery and for sending limits.
• Is BCC safe for confidential data? It only hides the address. Use an encrypted channel for confidential content.

References and further reading

• RFC 5322: Internet Message Format
• RFC 5321: Simple Mail Transfer Protocol