mail and sendmail and return path

[Enrico]

PHP.
it's Known that using mail function "Return-path" option doesn't works if you aren't root:
mail("ciccio@ciccio.com", $subj, $data,
"From: $from\nReply-To: webmaster@ciccio.com\nBcc: $bcc\nX-Mailer: PHP/" . phpversion()."\nReturn-Path: <ciccio@ciccio.com>\n")

but I used this function:

function send_mail($to,$bcc, $from,$return, $subject, $body)
{
$fp = popen("/usr/sbin/sendmail -f$return -t", "w");
fputs($fp, "To: $to\n");
fputs($fp, "Bcc: $bcc\n");
fputs($fp, "From:$from\n");
fputs($fp, "Subject: $subject\n\n");
fputs($fp, "$body");
pclose($fp);

}

the important point is "sendmail -f$return";
this in an other server (not HR) has always worked but now in HR server return option doesn't work ("bcc" and "to" yes).

Suggestions?
thanks