Core_Email::cc

public function cc($cc)
{
    $cc = $this->clean_email($this->_str_to_array($cc));

    if ($this->validate)
    {
        $this->validate_email($cc);
    }

    $this->set_header('Cc', implode(', ', $cc));

    if ($this->_get_protocol() === 'smtp')
    {
        $this->_cc_array = $cc;
    }

    return $this;
}