Entering an address in the Bcc field makes it invisible to other recipients of that email.
Here’s how to add Bcc recipients in Gmail.
Bcc also keeps people’s contact information private.

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Bcc isn’t without its downside, however.
People in corporate tweaks sometimes use this field to loop in supervisors or coworkers surreptitiously.
SelectComposeto start a new email.

SelectBccon the right side of theNew Messagewindow.
Another way to toggle this field is to pressCtrl+Shift+Bin Windows orCommand+Shift+Bin macOS.
Enter the primary recipients in theTosection.

These addresses are visible to every recipient.
Tohide the addresses of all recipients, leave theTofield blank, or type your email address.
In theBccfield, enter the email addresses you want to hide but to which you are sending the email.
Edit your message as you see fit and selectSend.