Mail thru PHP

Ok here's my query:
I have this block of code:

$mailpost = $mailpost;
$mailpost = str_replace("{setting_site_name}", $setting_site_name, $mailpost);
$mailpost = str_replace("{setting_site_url}", $setting_site_url, $mailpost);
$mailpost = str_replace("{setting_mail_email}", $setting_mail_email, $mailpost);
$mailpost = str_replace("{post_poster}", $cookie_username, $mailpost);
$mailpost = str_replace("{post_headline}", $headline, $mailpost);
$mailpost = str_replace("{post_date}", date("M d, Y", time()), $mailpost);
$mailpost = str_replace("{post_post}", $post, $mailpost);
$to = "";
$query = mysql_query("SELECT * FROM members");
while ($member = mysql_fetch_array($query)) {
if ($to == "") {$to = $member['email'];}
else {$to .= ", " . $member['email'];}
}
$from = "from: " . $setting_mail_email;
mail ($to, $setting_site_name, $mailpost, $from) or $emailsuccess = "Failure sending email.";
if ($emailsuccess == "") {$emailsuccess = "Email Sent Successfully.";}
}


Now what I need to do is instead of dumping all of my users emails into the To field in the email I want to put them all in
the bcc field to hide their emails from one another.

I changed it to this:

$mailpost = $mailpost;
$mailpost = str_replace("{setting_site_name}", $setting_site_name, $mailpost);
$mailpost = str_replace("{setting_site_url}", $setting_site_url, $mailpost);
$mailpost = str_replace("{setting_mail_email}", $setting_mail_email, $mailpost);
$mailpost = str_replace("{post_poster}", $cookie_username, $mailpost);
$mailpost = str_replace("{post_headline}", $headline, $mailpost);
$mailpost = str_replace("{post_date}", date("M d, Y", time()), $mailpost);
$mailpost = str_replace("{post_post}", $post, $mailpost);
$bcc = "";
$query = mysql_query("SELECT * FROM members");
while ($member = mysql_fetch_array($query)) {
if ($bcc == "") {$bcc = $member['email'];}
else {$bcc .= ", " . $member['email'];}
}
$from = "from: " . $setting_mail_email;
mail ($bcc, $setting_site_name, $mailpost, $from) or $emailsuccess = "Failure sending email.";
if ($emailsuccess == "") {$emailsuccess = "Email Sent Successfully.";}
}


But it is still outputing everyone's emails in the To field. Can anyone show me what I am diong wrong. Also what would be the line to include to make these be html emails? Thanks.