CC and BCC are available when you reply to a lead in Master Inbox. They aren't available on campaign emails.
TL;DR
When you reply to a lead in Master Inbox, you can add CC or BCC recipients.
Use CC to bring your main business email into the conversation once a lead shows interest.
Use BCC for a private copy, for example for your CRM.
Replying to everyone keeps the original recipients and CCs. You can't remove a CC that was already on the thread.
When you'd use this
Your campaigns send from dedicated sending inboxes, separate from your main business domain, which protects your main domain. Once a lead replies with interest, you're in a real sales conversation. CC lets you bring your main business email into the thread at that moment, without leaving Master Inbox.
Step-by-step
Open Master Inbox (next.listkit.io/master-inbox) and open the conversation you want to answer.
Start your reply, then add CC or BCC recipients in the reply window.
Type the email address you want to add. This is usually your main business email.
Write your reply and send it.
CC or BCC?
CC (visible to the lead): use it to move the conversation to your main business email. The lead sees the address and can reply to it directly.
BCC (hidden from the lead): use it for a private copy of your own message, for example for your CRM. A BCC address doesn't receive the lead's later replies. To log every positive reply automatically, use webhooks: How do I send ListKit events to my CRM or other tools with webhooks?.
Expected outcome
Once you CC your main business email, the lead's reply-all responses reach both Master Inbox and your main inbox, and you can continue from your main domain. With BCC, only your own message is copied.
FAQ
Can I CC or BCC any email address, or only my own?
Any address, for example a colleague, an account manager or a CRM inbox.
Will the lead see my main email address if I use BCC?
No. BCC is hidden from everyone else on the email. Only CC is visible.
Can I add more than one address?
Yes. Add each address separately.
Can I CC or BCC on my campaign emails?
No. CC and BCC are only available when you reply in Master Inbox.
Can I remove someone who was already CC'd on the thread?
No. When you reply to everyone, the original recipients and CCs stay on the thread.