Multiple User Mail Send.

If you need to send one identical e-mail to all 200 recipients, the bcc field is just fine. You can use a string or an array with all recipients.

PHP Code:

$this->email->bcc($recipients); 


If every recipient must get an e-mail with personalized information, then you should send the mails in a foreach loop, using an array.
Most times, I use a view file. I pass the variable information to the view and let the output being returned as a string.

PHP Code:

$this->load->library('email');
//$recipients is an array of objects or arrays (records)
Foreach($recipients as $mailto) {
    //$mailto is 1 record (object of array), containing e-mail address, name, etc.
    $message = $this->load->view('massmail', $mailto, TRUE); 
    //now, $message is a string with the complete e-mail body.
    $this->email->to($mailto['address']);
    $this->email->subject('This e-mail is about...');
    $this->email->from('[email protected]');
    $this->email->message($message);
    $this->email->send();
}