BCC in email: what it means and when to use it

BCC stands for blind carbon copy. When you put an email address in the BCC field, that person receives a copy of the message, but nobody else on the email can see that they were included. BCC is how you send a copy privately - the people in the To and CC fields never learn who was blind copied.

What does BCC mean in email?

BCC means blind carbon copy. The term is a holdover from typewriters, where a carbon copy was a duplicate page made with a sheet of carbon paper. A blind carbon copy is a duplicate sent to someone whose address is hidden from everyone else on the message.

Every email you send has three recipient fields:

• To is for the primary recipients, the people the message is actually addressed to.
• CC (carbon copy) is for people you want to keep in the loop. Everyone can see who is in the To and CC fields.
• BCC (blind carbon copy) is for people you want to copy privately. Their addresses are not shown to anyone else, and the other recipients cannot tell that a BCC field was used at all.

So the short version: if you want someone to have a copy but you do not want the rest of the recipients to know, you put them in BCC.

What is the difference between CC and BCC?

The difference between CC and BCC is visibility. CC recipients are public - everyone on the email sees their address. BCC recipients are hidden - no one except the sender knows they received the message. Here is how all three fields compare:

A useful rule of thumb: use To for the people who need to act, CC for people who should be aware, and BCC for people who should have a copy without the group knowing.

When should you use BCC?

There are three situations where BCC is the right tool:

1. Mass emails that protect privacy. When you send one message to many people who do not know each other - an announcement, an update, an invitation - put your own address in To and everyone else in BCC. That way no recipient sees the full list of addresses. Dropping dozens of strangers into the To or CC field instead exposes everyone's email address to everyone, which is both bad etiquette and, in some regions, a privacy violation you can be fined for.
2. Quietly looping in a manager or colleague. If you want your boss to see that you replied to a client, or you want a teammate to have a record of a conversation, BCC lets them receive the message without signalling to the client that anyone else is watching.
3. Moving people off a thread. In a long reply chain, you can write something like "moving Sam to BCC" and shift a person from CC to BCC. They get this final message for closure, but they are dropped from the addresses on any further replies, so their inbox stops filling up.

How to BCC in Gmail, Outlook, and Apple Mail

The BCC field is hidden by default in most email clients. Here is how to reveal and use it in each.

Gmail

1. Click Compose to start a new message.
2. In the top right of the To line, click Bcc.
3. Type the addresses you want to blind copy into the Bcc field.
4. Write your message and click Send.

Outlook

1. Start a new email with New mail.
2. On the Options tab (or the compose toolbar), click Bcc to show the field.
3. Add the addresses you want to hide into the Bcc field.
4. Click Send.

Apple Mail

1. Open a new message.
2. If the Bcc field is not showing, click the arrows button at the left of the header fields and choose Bcc Address Field, or enable it from the View menu.
3. Add addresses to the Bcc field.
4. Click Send.

BCC etiquette and pitfalls

BCC is quiet by design, and that is exactly where it gets people into trouble.

• Reply-all can blow the cover. A BCC recipient still has a working copy of the email. If they hit reply-all, their reply can reveal that they were secretly on the thread. Never assume BCC is invisible once the message leaves your outbox.
• CC leaks addresses. The most common privacy mistake is emailing a large group with everyone in CC. Every recipient can now see - and harvest - every other address. BCC is the fix. Treat exposed address lists the way you would treat any other data leak.
• It can read as sneaky. Blind-copying someone into a tense conversation to have a silent witness is a habit that damages trust if it comes out. Use BCC for privacy and tidiness, not surveillance.

How does BCC work at the SMTP level?

Here is the part most people never see. An email address does not have to appear in the message headers for the message to be delivered to it. When a mail server sends a message, it does two separate things: it lists the envelope recipients using SMTP RCPT TO commands, and it writes the visible To: and Cc: header lines.

The BCC trick is that a blind-copied address goes into RCPT TO - so the server delivers a copy to that mailbox - but it is deliberately left out of the headers the recipients can read. That gap between the delivery envelope and the visible headers is exactly why BCC is invisible: the message arrives, but nothing in the copy everyone else received names the blind recipient. This is also why understanding what "queued" means and how delivery works matters once you send at scale.

How to send BCC with an email API

If you are building software that sends email, you do not manipulate SMTP headers by hand - you pass a bcc array to your email API and it handles the envelope for you. With AgenticEmail, the send endpoint accepts to, cc, and bcc fields side by side:

curl -X POST https://api.agenticemail.dev/v1/inboxes/ibx_123/messages/send \
  -H "Authorization: Bearer $AGENTICEMAIL_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "to": ["customer@example.com"],
    "cc": ["team@example.com"],
    "bcc": ["archive@example.com"],
    "subject": "Your order has shipped",
    "text": "Hi - your order is on its way."
  }'

The archive@example.com address receives a full copy, but neither the customer nor the team sees it in their headers - the same blind-copy behavior your mail client gives you, exposed as a clean field. For the full request and response shape, see the API docs, and if you are sending from JavaScript, the send email API guide walks through it end to end. If your automated messages should not invite replies, pair BCC with a proper no-reply address.

Frequently asked questions

Can BCC recipients see each other?

No. Each BCC recipient sees only their own copy. They cannot see other BCC recipients, and they cannot tell how many people were blind copied. That privacy between BCC recipients is the whole point of the field.

Can BCC recipients reply all?

Yes, and this is the main risk with BCC. A blind-copied recipient has a normal email in their inbox, so if they reply all, their response can expose that they were on the original message. If you need someone to stay hidden, tell them not to reply all.

Do BCC recipients see the To and CC lists?

Yes. BCC hides the blind recipients from everyone else, but a BCC recipient can still see who was in the To and CC fields. Blind copying is only blind in one direction: it hides the BCC person, not the visible recipients.

Does BCC show in the email header?

Not in the copy other recipients receive. The blind-copied address is delivered through the SMTP envelope rather than the visible headers, so nothing in the message tells the To and CC recipients that a BCC was used. This is why BCC is genuinely invisible to them.

What does "moving someone to BCC" mean?

It means shifting a person from the To or CC field into BCC on your next reply, usually to give them a final copy while dropping them from the ongoing thread. It is a polite way to say "you are caught up, I will stop filling your inbox now."

Is BCC private and secure?

BCC is private in the sense that recipients cannot see each other, but it is not encryption. The addresses still exist in your outbox and on the sending mail server, and any BCC recipient can voluntarily reveal that they were included. Use BCC for courtesy and address privacy, not for confidentiality that has to hold up against a determined party.