添加附件选项后联系表单无法发送，求附件字段验证方案

Hey there! Let's figure out why your contact form stopped sending emails after adding attachments. I spotted a few key issues in your PHP code that are causing this problem, along with clear fixes to get it working again:

1. Broken Attachment Validation Check #

Your current check if (empty($_FILES["attachment"])) will always return false—even when no files are selected—because $_FILES["attachment"] is an array structure that exists regardless of uploads. Instead, we need to validate if any uploaded file is actually valid:

Replace your existing attachment validation code with this:

$attachment_error = "";
$has_valid_attachment = false;

// Check if any uploaded file is valid
if (isset($_FILES['attachment']['name'])) {
    foreach ($_FILES['attachment']['name'] as $index => $filename) {
        // Verify file was uploaded without errors and has a name
        if (!empty($filename) && $_FILES['attachment']['error'][$index] === UPLOAD_ERR_OK) {
            $has_valid_attachment = true;
            break;
        }
    }
}

// Uncomment below if you require at least one attachment
// if (!$has_valid_attachment) {
//     $attachment_error = "Palun sisesta enda eluloo fail";
// }

2. Undefined Message Variable When No Attachments Exist #

Right now, if no attachments are uploaded, $datamsg is never initialized. This causes the mail() function to fail because it's trying to send an undefined value. We'll fix this by setting a base message structure that works with or without attachments.

3. Inconsistent MIME Header & Attachment Handling #

Your code overwrites headers only when attachments exist, leading to broken email formatting. Here's the corrected full mail-handling block (replace your existing mail logic with this):

if ($name_error == '' && $email_error == '' && $message_error == '' && ($attachment_error == '' || $has_valid_attachment)) {
    $to = 'myemail@gmail.com';
    $subject = 'Eesti Elulood';
    $plain_message = "Sulle saadeti kiri Rannu koguduse kodulehelt.\n\nSaatja nimi: $thename\n\nSaatja email: $email\n\nSõnum: $message";

    // Setup MIME boundary for multi-part emails
    $semi_rand = md5(uniqid(time()));
    $mime_boundary = "==Multipart_Boundary_x{$semi_rand}x";

    // Base headers (works with or without attachments)
    $headers = "From: " . '=?UTF-8?B?' . base64_encode($thename) . '?=' . " <$email>" . PHP_EOL;
    $headers .= "Reply-To: " . '=?UTF-8?B?' . base64_encode($thename) . '?=' . " <$email>" . PHP_EOL;
    $headers .= "Return-Path: $email" . PHP_EOL;
    $headers .= "MIME-Version: 1.0" . PHP_EOL;
    $headers .= "Content-Type: multipart/mixed;" . PHP_EOL;
    $headers .= " Boundary=\"{$mime_boundary}\"";

    // Initialize message content
    $datamsg = "This is a multi-part message in MIME format." . PHP_EOL . PHP_EOL;
    $datamsg .= "--{$mime_boundary}" . PHP_EOL;
    $datamsg .= "Content-Type: text/plain; Charset=\"UTF-8\"" . PHP_EOL;
    $datamsg .= "Content-Transfer-Encoding: 8bit" . PHP_EOL . PHP_EOL;
    $datamsg .= $plain_message . PHP_EOL . PHP_EOL;

    // Process valid attachments
    if (isset($_FILES['attachment']['name'])) {
        for ($index = 0; $index < count($_FILES['attachment']['name']); $index++) {
            $filename = $_FILES['attachment']['name'][$index];
            $tmp_path = $_FILES['attachment']['tmp_name'][$index];
            $upload_error = $_FILES['attachment']['error'][$index];

            // Only process files that uploaded successfully
            if (!empty($filename) && $upload_error === UPLOAD_ERR_OK && is_readable($tmp_path)) {
                $file_content = file_get_contents($tmp_path);
                if ($file_content !== false) {
                    $data_file = chunk_split(base64_encode($file_content));
                    $datamsg .= "--{$mime_boundary}" . PHP_EOL;
                    $datamsg .= "Content-Type: application/octet-stream; Name=\"{$filename}\"" . PHP_EOL;
                    $datamsg .= "Content-Disposition: attachment; Filename=\"{$filename}\"" . PHP_EOL;
                    $datamsg .= "Content-Transfer-Encoding: base64" . PHP_EOL . PHP_EOL . $data_file . PHP_EOL . PHP_EOL;
                }
            }
        }
    }

    // Close the MIME boundary
    $datamsg .= "--{$mime_boundary}--";

    // Remove the @ to see debugging errors (restore it later)
    if (mail($to, '=?UTF-8?B?' . base64_encode($subject) . '?=', $datamsg, $headers, "-f$email")) {
        $success = "Täname! Sõnum saadeti edukalt.";
    } else {
        $error = "Vabandust, kuid sõnumit ei saanud saata. Palun proovige uuesti!";
        // Uncomment below to log errors for debugging
        // error_log("Mail failed: " . print_r(error_get_last(), true));
    }
}

4. Fix the Form Redirect Issue #

When you submit the form, it jumps to index.php because $_SERVER['PHP_SELF'] points to your main file. To keep users on the form page and show success/error messages, add this redirect logic right after setting $success or $error:

// Store messages in session and redirect back to the form
session_start();
$_SESSION['success'] = $success;
$_SESSION['error'] = $error;
$_SESSION['thename'] = $thename;
$_SESSION['email'] = $email;
header("Location: " . $_SERVER['HTTP_REFERER']);
exit;

Then update your form HTML to pull these values from the session:

<?php
session_start();
$success = isset($_SESSION['success']) ? $_SESSION['success'] : '';
$error = isset($_SESSION['error']) ? $_SESSION['error'] : '';
$thename = isset($_SESSION['thename']) ? $_SESSION['thename'] : '';
$email = isset($_SESSION['email']) ? $_SESSION['email'] : '';

// Clear session after displaying messages
unset($_SESSION['success'], $_SESSION['error'], $_SESSION['thename'], $_SESSION['email']);
?>

Quick Debugging Tips #

• Remove the @ before mail() temporarily to see PHP errors related to mail sending
• Check your server's mail logs (typically /var/log/mail.log on Linux) for delivery issues
• Ensure your server allows file uploads and adjust upload_max_filesize/post_max_size in php.ini if you need to accept larger files

内容的提问来源于stack exchange，提问作者Ilona