Symfony 3 - Swift_Mailer - 发送电子邮件但输入失败并返回0

Question

我有一个使用SwiftMailer发送电子邮件的开发。

我有一个完美的开发服务器（使用PHP 5）

我有一个生产服务器，其中有PHP 7（并且服务器非常处女，配置很少），它提出了这些问题

电子邮件发送完好但邮件程序返回0.

我的电子邮件发送功能是：

public function sendEmail ($email) {
    $transport = \Swift_MailTransport::newInstance("localhost", 25);
    $mailer = \Swift_Mailer::newInstance($transport);

    $message = \Swift_Message::newInstance("Recuperación de Contraseña");


    if (isset($email["subject"]) && !empty($email["subject"])) {
        $message->setSubject($email["subject"]);
    }

    if (isset($email["from"]) && !empty($email["from"])) {
        $message->setFrom($email["from"]);
    }

    if (isset($email["to"]) && !empty($email["to"])) {
        $message->setTo($email["to"]);
        $message->setReadReceiptTo($email["to"]);

    }

    if (isset($email["embed_images"]) && !empty($email["embed_images"])) {
        foreach ($email["embed_images"] as $embedImage_key=>$embedImage_value) {
            if (!empty($embedImage_value)) {
                $email["embed_images"][$embedImage_key] = $message->embed(\Swift_Image::fromPath($embedImage_value));
            }
        }
    }

    $email["parameters"] = array_merge($email["parameters"], array("embed_images" => $email["embed_images"]));

    if (!isset($email["body"]) || empty($email["body"])) {
        $message->setBody(
            $this->renderView(
                $email["template"],
                $email["parameters"]
            ), 'text/html'
        );

    }

    if (isset($email["attach_images"]) && !empty($email["attach_images"])) {
        foreach ($email["attach_images"] as $attachImage_key=>$attachImage_value) {
            if (!empty($attachImage_value)) {
                $message->attach(Swift_Attachment::fromPath($attachImage_value));
            }
        }
    }

    $statusSend = true;

    $logger = new \Swift_Plugins_Loggers_ArrayLogger;
    //$logger = new \Swift_Plugins_Loggers_EchoLogger; //echo messages in real-time
    $mailer->registerPlugin(new \Swift_Plugins_LoggerPlugin($logger));



    if (!$mailer->send($message, $failures)) {
        $statusSend = false;

        echo "Failures:";
        print_r($failures);
    }

    echo $logger->dump(); //not needed if using EchoLogger plugin


    return $statusSend;
}

并通过

if (!$mailer->send($message, $failures)) {

是Swift_Mailer的问题吗？来自PHP？

由于