thanx for the pointer! I've have a fiddle with your suggestion this is what I've come up with:
// get the total number of rows
$totalRows_Recordset4 = mysql_num_rows($Recordset4);
// set when you want to be notified
if (($totalRows_Recordset4 == 25) || ($totalRows_Recordset4 == 50) || ($totalRows_Recordset4 == 100))
// if a specified number of rows have been reached then send an email with that number
{mail("me@myemail.com","questionnaire results","replies so far ". $totalRows_Recordset4,"From: me@myemail.com\n");}