The Blind Carbon Copy option in Webmail, allows you to send a copy of your email to an email address that the recipient of the message will not be able to see.
To BCC (Blind Carbon Copy) a recipient:
Select a message (this could be a message you have received, or you could create a new message by pressing the New Mail icon in your inbox toolbar).
If this is a message you received, click on the Reply or Forward option in your toolbar.
Once the message is open, press the Bcc icon on the toolbar of the message.
Type in the email address you want to send the message to in the Bcc field of the message.