PayPal 使用电子邮件功能时IPN不起作用

我认为您的邮件功能失败并给出了 200 以外的标头，PayPal期望这就是 8 次重试的原因。无论如何，我编辑了代码并将 mail（） 函数放在 try catch 块中并记录了错误。

    <?php
        // CONFIG: Enable debug mode. This means we'll log requests into 'ipn.log' in the same directory.
        // Especially useful if you encounter network errors or other intermittent problems with IPN (validation).
        // Set this to 0 once you go live or don't require logging.
        define("DEBUG", 1);
        // Set to 0 once you're ready to go live
        define("USE_SANDBOX", 1);
        define("LOG_FILE", "./ipn.log");
        $raw_post_data = file_get_contents('php://input');
        $raw_post_array = explode('&', $raw_post_data);
        $myPost = array();
        foreach ($raw_post_array as $keyval) {
            $keyval = explode ('=', $keyval);
            if (count($keyval) == 2)
                $myPost[$keyval[0]] = urldecode($keyval[1]);
        }
        // read the post from PayPal system and add 'cmd'
        $req = 'cmd=_notify-validate';
        if(function_exists('get_magic_quotes_gpc')) {
            $get_magic_quotes_exists = true;
        }
        foreach ($myPost as $key => $value) {
            if($get_magic_quotes_exists == true && get_magic_quotes_gpc() == 1) {
                $value = urlencode(stripslashes($value));
            } else {
                $value = urlencode($value);
            }
            $req .= "&$key=$value";
        }
        // Post IPN data back to PayPal to validate the IPN data is genuine
        // Without this step anyone can fake IPN data
        if(USE_SANDBOX == true) {
            $paypal_url = "https://www.sandbox.paypal.com/cgi-bin/webscr";
        } else {
            $paypal_url = "https://www.paypal.com/cgi-bin/webscr";
        }
        $ch = curl_init($paypal_url);
        if ($ch == FALSE) {
            return FALSE;
        }
        curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
        curl_setopt($ch, CURLOPT_POST, 1);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $req);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 1);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
        curl_setopt($ch, CURLOPT_FORBID_REUSE, 1);
        if(DEBUG == true) {
            curl_setopt($ch, CURLOPT_HEADER, 1);
            curl_setopt($ch, CURLINFO_HEADER_OUT, 1);
        }
        // Set TCP timeout to 30 seconds
        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 30);
        curl_setopt($ch, CURLOPT_HTTPHEADER, array('Connection: Close'));
        $res = curl_exec($ch);
        if (curl_errno($ch) != 0) // cURL error
            {
            if(DEBUG == true) { 
                error_log(date('[Y-m-d H:i e] '). "Can't connect to PayPal to validate IPN message: " . curl_error($ch) . PHP_EOL, 3, LOG_FILE);
            }
            curl_close($ch);
            exit;
        } else {
                // Log the entire HTTP response if debug is switched on.
                if(DEBUG == true) {
                    error_log(date('[Y-m-d H:i e] '). "HTTP request of validation request:". curl_getinfo($ch, CURLINFO_HEADER_OUT) ." for IPN payload: $req" . PHP_EOL, 3, LOG_FILE);
                    error_log(date('[Y-m-d H:i e] '). "HTTP response of validation request: $res" . PHP_EOL, 3, LOG_FILE);
                }
                curl_close($ch);
        }
        // Inspect IPN validation result and act accordingly
        // Split response headers and payload, a better way for strcmp
        $tokens = explode("'r'n'r'n", trim($res));
        $res = trim(end($tokens));
        if (strcmp ($res, "VERIFIED") == 0) {

            try{
mail('try@website.com', 'New Order', 'New Order', 'From: support@website.com');
}
catch(Exception $e){
error_log(date('[Y-m-d H:i e] '). "Email could not be sent. Error" . $e->getMessage(). PHP_EOL, 3, LOG_FILE);
}

            if(DEBUG == true) {
                error_log(date('[Y-m-d H:i e] '). "Verified IPN: $req ". PHP_EOL, 3, LOG_FILE);
            }
        } else if (strcmp ($res, "INVALID") == 0) {
            // log for manual investigation
            // Add business logic here which deals with invalid IPN messages
            if(DEBUG == true) {
                error_log(date('[Y-m-d H:i e] '). "Invalid IPN: $req" . PHP_EOL, 3, LOG_FILE);
            }
        }
        ?>

Okey 我终于找到了解决方案，这仅适用于使用虚拟专用服务器的人。对我来说，问题是邮件功能花费的时间太长，可能会在 IPN 侦听器中产生超时，

要解决此问题：
- 首先，您在命令提示符下获得主机名提示hostname
- 然后我编辑主机文件：sudo nano /etc/hosts
-----------并更改此行 -> 127.0.0.1 localhost myhostname
-----------到这一行 -> 127.0.0.1 localhost localhost.localdomain myhostname

源：
http://deeemm.com/entry/general/fix-your-painfully-slow-php-mail-function