PHP表单邮件无法附加上传文件问题排查求助

嘿，我仔细看了你的代码，发现几个关键问题导致附件没法正常发送，咱们一个个来解决：

1. 表单缺少文件上传必需的enctype属性 #

HTML表单要支持文件上传，必须在<form>标签里加上enctype="multipart/form-data"，不然浏览器不会把文件数据提交到服务器，$_FILES数组会是空的。

修改后的表单开头：

<form action="../php/contact-us-main.php" method="POST" enctype="multipart/form-data">

2. 文件字段名不匹配 #

你的表单里文件输入框的name是attachment，但PHP代码里却用了$_FILES['my_file']——这俩名字必须完全一致！把PHP里的my_file全改成attachment。

修正后的文件变量部分：

$tmp_name = $_FILES['attachment']['tmp_name'];
$name = $_FILES['attachment']['name'];
$size = $_FILES['attachment']['size'];
$type = $_FILES['attachment']['type'];
$error = $_FILES['attachment']['error'];

3. 邮件头被错误覆盖 #

你前面花了功夫构建支持多部分邮件的$headers（包含MIME边界、多部分类型），但后面又重新赋值了$headers = "From: $email_from \r\n";，直接把之前的配置冲没了！这会导致邮件变成纯文本格式，附件根本无法被识别。

要把后面的From和Reply-To追加到之前的headers里，而不是重新赋值：

修正后的headers部分：

// 先定义$email_from，再用在headers里
$email_from = 'xxxxxxxxxxxxxxxxxxxx';
$headers = "MIME-Version: 1.0\r\n";
$headers .= "Reply-To: $first $surname <$email>\r\n";
$headers .= "From: $email_from\r\n";
$headers .= "Content-Type: multipart/mixed; boundary = $boundary\r\n";

4. 邮件主体用错了变量 #

你构建了包含附件的$body变量，但调用mail()函数时传的是纯文本的$email_body——相当于完全没用到带附件的内容！必须把$body作为邮件主体传进去。

修正后的mail调用：

mail($to, $email_subject, $body, $headers);

5. 未定义的变量导致附件信息错误 #

你在构建附件部分用了$file_type和$file_name，但这俩变量根本没定义，应该用之前获取的$type和$name，还要记得添加邮件的结束边界：

修正后的附件部分代码：

$body .= "--$boundary\r\n";
$body .= "Content-Type: $type; name=\"$name\"\r\n";
$body .= "Content-Disposition: attachment; filename=\"$name\"\r\n";
$body .= "Content-Transfer-Encoding: base64\r\n";
$body .= "X-Attachment-Id: ".rand(1000, 99999)."\r\n\r\n";
$body .= $encoded_content;
// 必须添加结束边界，否则邮件可能解析异常
$body .= "--$boundary--";

完整修正后的PHP代码片段（关键部分） #

<?php 
if($_POST['button'] && isset($_FILES['attachment'])){ 
    $department = $_POST['department']; 
    $title = $_POST['title']; 
    $first = $_POST['first']; 
    $surname = $_POST['surname']; 
    $email = $_POST['email']; 
    $number = $_POST['number']; 
    $userMessage = $_POST['userMessage']; 

    // 修正：使用正确的字段名attachment
    $tmp_name = $_FILES['attachment']['tmp_name']; 
    $name = $_FILES['attachment']['name']; 
    $size = $_FILES['attachment']['size']; 
    $type = $_FILES['attachment']['type']; 
    $error = $_FILES['attachment']['error']; 

    // 读取文件并编码
    $handle = fopen($tmp_name, "r"); 
    $content = fread($handle, $size); 
    fclose($handle); 
    $encoded_content = chunk_split(base64_encode($content)); 

    $boundary = md5("random"); 
    $email_from = 'xxxxxxxxxxxxxxxxxxxx'; 

    // 修正：正确构建headers，不覆盖之前的配置
    $headers = "MIME-Version: 1.0\r\n";
    $headers .= "Reply-To: $first $surname <$email>\r\n";
    $headers .= "From: $email_from\r\n";
    $headers .= "Content-Type: multipart/mixed; boundary = $boundary\r\n";

    // 构建带附件的邮件主体
    $body = "--$boundary\r\n";
    $body .= "Content-Type: text/plain; charset=ISO-8859-1\r\n";
    $body .= "Content-Transfer-Encoding: base64\r\n\r\n";
    // 把文本信息整合到body里
    $text_content = "User title: $title. \n". 
                    "The department this message is for is: $department.\n". 
                    "User First Name: $first.\n". 
                    "User Surname Name: $surname. \n". 
                    "User email: $email.\n". 
                    "User Contact Number: $number.\n". 
                    "User Message is: $userMessage.\n";
    $body .= chunk_split(base64_encode($text_content));

    // 修正：使用正确的变量$type和$name
    $body .= "--$boundary\r\n";
    $body .= "Content-Type: $type; name=\"$name\"\r\n";
    $body .= "Content-Disposition: attachment; filename=\"$name\"\r\n";
    $body .= "Content-Transfer-Encoding: base64\r\n";
    $body .= "X-Attachment-Id: ".rand(1000, 99999)."\r\n\r\n";
    $body .= $encoded_content;
    // 必须添加结束边界
    $body .= "--$boundary--";

    $email_subject = "New Email Form Submission from $first.";
    $to = 'xxxxxxxxxxxx'; 

    // 修正：传入正确的$body作为邮件内容
    mail($to, $email_subject, $body, $headers); 
    header('Location: https://www.xxxxxxxxxxx.com/pages/thank-you.html'); 
} 
?>

另外，建议加上文件上传的错误检查（比如if($error !== UPLOAD_ERR_OK)时提示用户上传失败），避免文件上传出问题时还继续发送无附件的邮件。

内容的提问来源于stack exchange，提问作者Hunktydunkaty