Krijg geen bevestigins mail verstuurd

Ik heb een script toevoegen aan database gaat prima, betreft reserveringen voor woningen maar de administrator moet mail krijgen er heeft iemand gereserveerd voor die en die woning. Ik krijg het niet voor elkaar heb geprobeerd code voor email versturen er tussen te zetten maar dan geeft ie de pagina niet weer of er komt niets aan. Onderstaande deel van het script waar ik denk dat de het ergens moet tussen geplaatst worden maar ik kom er niet uit.

if(isset($_POST['naam'])) {
$cal_checkname = checkname($_POST['naam'], 5);
$cal_checkstreet = checkstreet($_POST['straat']);
$cal_checkcity = checkcity($_POST['plaats']);
$cal_checkpostalcodeNL = checkpostalcodeNL($_POST['postcode']);
$cal_checkphonenrNL = checkphonenrNL($_POST['telefoonnummer']);
$cal_checkmailaddress = checkmailaddress($_POST['mailadres']);
$cal_checkfromtilldates = checkfromtilldates($_POST['van'], $_POST['tot'], $_POST['huisnaam']);
$cal_checkhouse = checkhouse($_POST['huis'], $_POST['huisnaam']);
$cal_checkhousenr = checkhousenr($_POST['huisnr']);

$cal_name = mysql_real_escape_string($_POST['naam']);
$cal_street = mysql_real_escape_string($_POST['straat']);
$cal_city = mysql_real_escape_string($_POST['plaats']);
$cal_postalcode = mysql_real_escape_string($_POST['postcode']);
$cal_phonenr = mysql_real_escape_string($_POST['telefoonnummer']);
$cal_mailaddress = mysql_real_escape_string($_POST['mailadres']);
$cal_from = $_POST['van'];
$cal_till = $_POST['tot'];
$cal_housenr = mysql_real_escape_string($_POST['huisnr']);
$cal_housename = mysql_real_escape_string($_POST['huisnaam']);
$cal_housedispname = mysql_real_escape_string($_POST['huis']);

if($cal_checkname && $cal_checkstreet && $cal_checkcity && $cal_checkpostalcodeNL && $cal_checkphonenrNL && $cal_checkmailaddress && $cal_checkfromtilldates && $cal_checkhouse && $cal_checkhousenr) {
//save in database
$cal_from = explode('-', $cal_from);
$cal_till = explode('-', $cal_till);
for($cal_i = 0; $cal_i < 3; $cal_i++) {
if(strlen($cal_from[$cal_i]) < 2) {
$cal_from[$cal_i] = '0' . $cal_from[$cal_i];
}

if(strlen($cal_till[$cal_i]) < 2) {
$cal_till[$cal_i] = '0' . $cal_till[$cal_i];
}
}

$cal_from = mysql_real_escape_string($cal_from[2] . '-' . $cal_from[1] . '-' . $cal_from[0]);
$cal_till = mysql_real_escape_string($cal_till[2] . '-' . $cal_till[1] . '-' . $cal_till[0]);

$cal_query = "SELECT calendar_id
FROM calendars
WHERE calendar_name = '" . $cal_housename . "'
AND calendar_dispname = '" . $cal_housedispname . "';";

$cal_resource = mysql_query($cal_query);
if($cal_resource) {
$cal_result = mysql_fetch_assoc($cal_resource);
$cal_calendar_id = intval($cal_result['calendar_id']);
} else {
//mysql error
print "Helaas is er een fout opgetreden.";
//print "De foutmelding is: " . mysql_error();
exit;
}

$cal_query = "INSERT INTO reservations
VALUES(NULL, '" . $cal_from . "', '" . $cal_till . "', " . $cal_calendar_id . ", 'r', '" . $cal_name . "', '" . $cal_street . "', '" . $cal_housenr . "',
'" . $cal_postalcode . "', '" . $cal_city . "', '" . $cal_phonenr . "', '" . $cal_mailaddress . "');";
if(mysql_query($cal_query)) {
?>Uw reservering is toegevoegd, <a href="showcalendar.php?c=<?php print $cal_housename ?>">keer terug</a>.<?php
} else {
//mysql error
print "Helaas is er een fout opgetreden.";
//print "De foutmelding is: " . $cal_mysql_error();
exit;
}
} else {
$cal_nameerror = !$cal_checkname;
$cal_streeterror = !$cal_checkstreet;
$cal_cityerror = !$cal_checkcity;
$cal_postalcodeerror = !$cal_checkpostalcodeNL;
$cal_phonenrerror = !$cal_checkphonenrNL;
$cal_mailaddresserror = !$cal_checkmailaddress;
$cal_fromtilldateserror = !$cal_checkfromtilldates;
$cal_houseerror = !$cal_checkhouse;
$cal_housenrerror = !$cal_checkhousenr;
$cal_showform = true;
print "<strong style=\"color: red;\">Niet alle velden zijn goed ingevuld!</strong><br><br>";
}
} else {
$cal_showform = true;
$cal_name = "";
$cal_street = "";
$cal_city = "";
$cal_postalcode = "";
$cal_phonenr = "";
$cal_mailaddress = "";
$cal_till = "";
$cal_housenr = "";
}

if($cal_showform) {
$cal_query = "SELECT *
FROM calendars
WHERE calendar_name = '" . mysql_real_escape_string($_GET['c']) . "';";
$cal_resource = mysql_query($cal_query);
if($cal_resource) {
if(mysql_num_rows($cal_resource) == 1) {
$cal_result = mysql_fetch_assoc($cal_resource);
$cal_house = $cal_result['calendar_dispname'];
} else {
print "Dit huis bestaat niet!";
exit;
}
} else {
print "Helaas is er een fout opgetreden!";
//print "De volgende fout trad op: " . mysql_error();
exit;
}