Most email clients, including Gmail, Yahoo, Microsoft Outlook, and Mozilla Thunderbird, give you the ability to send a single email to a large number of recipients. You can usually either choose to do so by CCing, which stands for "carbon copying," the recipients or by BCCing, or "blind carbon copying," them. The former simply sends a group email, while the latter conceals the identity of each of the involved contacts.
How To CC in an Email
You can CC email recipients simply by entering the list of addresses into the CC field, which is usually found just beneath the To field.
How To BCC in an Email
You can hide the identities of your recipients by entering their addresses into the BCC field instead of using the To or CC fields.