PHPMailer多收件人CC异常：抄送收件箱收到75份重复邮件问题

我数据库内有75个用户邮箱，通过表单传参到sendmail.php执行批量发送。设置抄送地址后，我的收件箱收到了75份抄送邮件，添加$mail->clearAddresses();后问题仍未解决。需求是给每个用户单独发送一封邮件，每封邮件同时抄送指定收件人。

当前问题代码 #

<?php

/**
     * Send email to a list of recipients with phpMailer.
 */

//============================================================ database connection
//   code goes here
// ============================================================= end db connection

use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\Exception;

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

//===================================================================
if(isset($_POST['send'])) {
     $administrator=    $_POST['administrator'] ;
     $sender=           $_POST['sender'];
     $from=             $_POST['sender'];
     $from_email=       $_POST['from_email'] ;
     $replyto=          $_POST['from_email'] ;
     $subject=          $_POST['subject'] ;
    $message =          $_POST['message'];
     $cc=               $_POST['cc'] ;
     $sig_block=        $_POST['sig_block'] ;
     $fileName=         $_POST['fileName'] ;

     $location = "PHPMailer/attachments/";
     $subject =  "$subject";
     $message =  "$message<p>$sig_block";

//===============================
$mail = new PHPMailer(true);

try {
//Server settings
        $mail->isSMTP();
        $mail->SMTPAuth   = true;
      
        $mail->Host          = 'smtp.xxx.com'; 
        $mail->Username      = 'email address';
        $mail->Password      = 'password';

        $mail->SMTPSecure    = PHPMailer::ENCRYPTION_STARTTLS;  
        $mail->SMTPKeepAlive = true;
        $mail->Port          = 587;

//Attachment
        if(strlen($fileName) >=4) {
            $mail->addAttachment($location.$fileName);
        }

//Content
        $mail->isHTML(true);
        $mail->Subject = $subject;
        $mail->Body = $message; 
        
//Recipients
        $mail->setFrom('email@domain', 'Webmaster'); 
        if(strlen($cc) >=4) {
            $mail->addCC($cc);
            }
        $mail->addReplyTo($replyto, $sender);   //Reply to sender email
        $mail->addAddress($from_email, $sender);  //copy sent to sender

//----------------------------------------------------------------------

// Access database 
     $sql= $conn->prepare("
          SELECT fname, lname, email 
          FROM members
          WHERE year_pd = '$year'
          ORDER BY lname
     ");

     $sql->execute(); 
     while ($row = $sql->fetch()) {  
           $fname= $row['fname']; 
           $lname= $row['lname']; 
           $to= $row['email'];

          $mail->clearAddresses() ;

}  // close while

} // close try
 catch (Exception $e) {
        echo 'Message could not be sent. Mailer Error: ', $mail->ErrorInfo;
    }
 
?>

问题根源 #

1. 未清理抄送列表：clearAddresses()仅清理收件人（To）地址，不会清除抄送（CC）地址，循环外添加的CC会被保留到每一封邮件中。
2. 核心逻辑缺失：循环内仅清理收件人，未添加数据库用户作为新收件人，也没有调用send()发送邮件。
3. 收件人配置错误：给自己的邮箱添加了固定收件人，且放在循环外，导致该地址被加入每封邮件的收件列表。

修正后的代码 #

<?php

/**
 * Send email to a list of recipients with phpMailer.
 */

//============================================================ database connection
//   code goes here
// ============================================================= end db connection

use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\Exception;

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

//===================================================================
if(isset($_POST['send'])) {
    $administrator = $_POST['administrator'];
    $sender = $_POST['sender'];
    $from_email = $_POST['from_email'];
    $replyto = $_POST['from_email'];
    $subject = $_POST['subject'];
    $message = $_POST['message'];
    $cc = $_POST['cc'];
    $sig_block = $_POST['sig_block'];
    $fileName = $_POST['fileName'];

    $location = "PHPMailer/attachments/";
    $message .= "<p>" . $sig_block;

    $mail = new PHPMailer(true);

    try {
        // 服务器配置（仅需设置一次）
        $mail->isSMTP();
        $mail->SMTPAuth = true;
        $mail->Host = 'smtp.xxx.com'; 
        $mail->Username = 'email address';
        $mail->Password = 'password';
        $mail->SMTPSecure = PHPMailer::ENCRYPTION_STARTTLS;  
        $mail->SMTPKeepAlive = true;
        $mail->Port = 587;

        // 邮件内容配置（仅需设置一次）
        $mail->isHTML(true);
        $mail->Subject = $subject;
        $mail->Body = $message; 
        $mail->setFrom('email@domain', 'Webmaster'); 
        $mail->addReplyTo($replyto, $sender);

        // 添加附件（仅需设置一次）
        if(strlen($fileName) >=4) {
            $mail->addAttachment($location . $fileName);
        }

        // 数据库查询（使用参数绑定避免SQL注入）
        $sql = $conn->prepare("
            SELECT fname, lname, email 
            FROM members
            WHERE year_pd = ?
            ORDER BY lname
        ");
        $sql->execute([$year]);

        // 循环发送邮件
        while ($row = $sql->fetch()) {  
            $toName = $row['fname'] . ' ' . $row['lname'];
            $toEmail = $row['email'];

            // 清理上一次的收件人和抄送列表
            $mail->clearAddresses();
            $mail->clearCCs();

            // 添加当前用户为收件人
            $mail->addAddress($toEmail, $toName);

            // 添加抄送地址（如果存在）
            if(strlen($cc) >=4) {
                $mail->addCC($cc);
            }

            // 给自己发送副本
            $mail->addAddress($from_email, $sender);

            // 发送邮件
            $mail->send();
        } 

        echo "所有邮件发送完成！";
    } catch (Exception $e) {
        echo '邮件发送失败：', $mail->ErrorInfo;
    } finally {
        // 关闭SMTP连接
        $mail->smtpClose();
    }
}
?>

关键修改说明 #

• 清理抄送列表：每次循环调用clearCCs()确保抄送地址不会重复添加。
• 循环内完成完整发送流程：在循环中添加收件人、抄送，调用send()发送邮件，保证每封邮件独立。
• SQL注入防护：将原代码中的字符串拼接改为参数绑定，提升安全性。
• 优化配置逻辑：将无需重复设置的服务器、内容、附件配置移到循环外，提升发送效率。
• 关闭SMTP连接：批量发送完成后调用smtpClose()释放连接资源。

内容的提问来源于stack exchange，提问作者Phil R