Paypal沙箱没有响应

我知道这里已经讨论了很多，但我花了一天的大部分时间试图修复这个错误，似乎没有取得任何进展

当我使用PayPals IPN模拟器发送模拟IPN时，我不断收到响应Live INVALID IPN

现在我认为这是因为我将它作为一个来自沙盒的测试发送，所以我尝试使用沙盒url，如下面所示，但如果我这样做，我根本没有收到响应

有人能告诉我哪里出了问题吗

<?php // PHP 4.1

// read the post from PayPal system and add 'cmd'
$req = 'cmd=_notify-validate';

foreach ($_POST as $key => $value) {
      $value = urlencode(stripslashes($value));
      $req .= "&$key=$value";
}

$email = ****;
// post back to PayPal system to validate
$header .= "POST /cgi-bin/webscr HTTP/1.0\r\n";
$header .= "Content-Type: application/x-www-form-urlencoded\r\n";
$header .= "Content-Length: " . strlen($req) . "\r\n\r\n";
$fp = fsockopen ('ssl://www.paypal.com', 443, $errno, $errstr, 30);
//$fp = fsockopen ('ssl://www.sandbox.paypal.com', 443, $errno, $errstr, 30);


// assign posted variables to local variables
$item_name = $_POST['item_name'];
$item_number = $_POST['item_number'];
$payment_status = $_POST['payment_status'];
$payment_amount = $_POST['mc_gross'];
$payment_currency = $_POST['mc_currency'];
$txn_id = $_POST['txn_id'];
$receiver_email = $_POST['receiver_email'];
$payer_email = $_POST['payer_email'];

if (!$fp) {
   // HTTP ERROR
} else {
   fputs ($fp, $header . $req);
while (!feof($fp)) {
$res = fgets ($fp, 1024);
if (strcmp ($res, "VERIFIED") == 0) {
    // check the payment_status is Completed
   // check that txn_id has not been previously processed
   // check that receiver_email is your Primary PayPal email
   // check that payment_amount/payment_currency are correct
   // process payment
   mail($email, "Live-VERIFIED IPN", $res . "\n\n" . $req);
}
else if (strcmp ($res, "INVALID") == 0) {
    // log for manual investigation
    mail($email, "Live-INVALID IPN", $res . "\n\n" . $req);
}
}
fclose ($fp);
}
?>

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发布此问题后，我在paypal开发人员身上发现了以下使用curl的示例，这对我来说是第一次，我收到了验证的回复

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