解决PHPMailer附件发送时序问题：首次失败刷新后成功的解决方案

<?php
// 引入PHPMailer类和设置文件
use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\SMTP;
use PHPMailer\PHPMailer\Exception;

require 'PHPMailer-master/src/PHPMailer.php';
require 'PHPMailer-master/src/SMTP.php';
require 'PHPMailer-master/src/Exception.php';

include 'settings.php'; // 包含设置文件

// 检查表单是否提交
if (isset($_POST['generate'])) {
    // 获取表单数据
    $name = ucwords($_POST['name']);
    $customerref = ($_POST['customerref']);
    $date = ($_POST['date']);
    $customeremail = ($_POST['customeremail']);
    $weight = ucwords($_POST['weight']);

    // 输入验证
    if ($name == "" || $weight == "" || $date == "" || $customeremail == "" || $customerref == "") {
        echo "<div class='alert alert-danger col-sm-6' role='alert'>并非所有表单字段都已填写。请重试。</div>";
    } else {
        // 提示信息
        echo "<div class='alert alert-success col-sm-6' role='alert'>恭喜！$name 的证书已生成并发送至 $customeremail。</div>";

        // --- 第一步：生成并保存证书图片 ---
        $image = "CSD-Certificates/certi.png";
        $createimage = imagecreatefrompng($image);

        $output = dirname(__FILE__) . "/CSD-Certificates/saved-certs/destruction-cert($customerref-$date).png";

        $white = imagecolorallocate($createimage, 254, 254, 254);
        $black = imagecolorallocate($createimage, 0, 0, 0);
        $rotation = 0;

        // 字体路径
        $drFont = "CSD-Certificates/TitilliumWeb-Regular.ttf";

        // 根据名称长度调整字体大小和位置
        $name_len = strlen($_POST['name']);
        $font_size = 50;
        $origin_x = 1600;
        if ($name_len > 7 && $name_len <= 12) { $font_size = 40; }
        elseif ($name_len > 12 && $name_len <= 15) { $font_size = 40; }
        // ... 其他长度判断

        // 写入文本到图片
        imagettftext($createimage, $font_size, $rotation, $origin_x, 700, $white, $drFont, $name);
        imagettftext($createimage, 50, $rotation, 2302, 900, $white, $drFont, $weight);
        imagettftext($createimage, $font_size, $rotation, 1850, 900, $white, $drFont, $date);
        imagettftext($createimage, $font_size, $rotation, 2200, 1980, $white, $drFont, $date);
        imagettftext($createimage, $font_size, $rotation, 2200, 2180, $white, $drFont, $customerref);

        // 保存生成的图片文件
        imagepng($createimage, $output, 3);
        // 释放内存
        imagedestroy($createimage);

        // --- 第二步：使用PHPMailer发送邮件 ---
        $mail = new PHPMailer(true); // 启用异常

        try {
            // 服务器设置
            $mail->isSMTP();
            $mail->Host       = 'mail.smtp2go.com';
            $mail->SMTPAuth   = true;
            $mail->Username   = 'refurbsa.com';
            $mail->Password   = 'Y2F6ejMxbGFseTUw';
            $mail->SMTPSecure = PHPMailer::ENCRYPTION_SMTPS;
            $mail->Port       = 465;

            // 收件人
            $mail->setFrom('sender@example.com', 'Electronic Cemetery');
            $mail->addAddress($customeremail); // 使用从表单获取的邮箱
            $mail->addReplyTo('replyto@example.com', 'Electronic Cemetery');

            // 添加附件 (确保 $output 路径的文件已存在)
            $mail->AddAttachment($output);

            // 内容
            $mail->isHTML(true);
            $mail->Subject = '您的电子废物处理证书';
            $mail->Body    = "您好 $name,<br><br>
感谢您使用我们的服务。您的回收请求已处理，我们已将销毁证书附加到此电子邮件中。
<br><br>
如果您对我们的服务感到满意，请花一点时间在 <a href='https://www.facebook.com/eastcoastewaste/reviews'>这里</a> 给予我们评价，我们将不胜感激。
<br><br>
我们期待未来能继续协助您处理所有电子废物需求。
<br><br>
祝您有美好的一天！
<br><br>
电子墓地团队";

            $mail->send();
        } catch (Exception $e) {
            echo "邮件无法发送。Mailer Error: {$mail->ErrorInfo}";
        }
    }
}
?>