邮件通信是现代社会不可或缺的一部分。PHP作为一种服务器端编程语言，通过自带的mail函数实现了像发送邮件这样的基本操作。本文将介绍在PHP中如何使用mail函数发送邮件，以及如何在邮件中添加附件和HTML内容。
发送简单的文本邮件非常简单，只需要写一行代码：
<?php
mail('recipient@example.com', 'Subject', 'Message');
?><form method="POST" action="upload.php" enctype="multipart/form-data">
<input type="file" name="fileToUpload">
<input type="submit" value="Upload">
</form><?php
$uploads_dir = '/path/to/uploads/directory/';
$filename = basename($_FILES['fileToUpload']['name']);
move_uploaded_file($_FILES['fileToUpload']['tmp_name'], $uploads_dir . $filename);$attachments = array('/path/to/file1', '/path/to/file2');
$boundary = '----=' . md5(uniqid(microtime()));
$headers = 'From: foo@example.com' . "\r\n";
$headers .= 'MIME-Version: 1.0' . "\r\n";
$headers .= 'Content-Type: multipart/mixed; boundary="' . $boundary . '"' . "\r\n";
$message = 'This is a multi-part message in MIME format.' . "\r\n\r\n";
$message .= '--' . $boundary . "\r\n";
$message .= 'Content-Type: text/plain; charset="iso-8859-1"' . "\r\n";
$message .= 'Content-Transfer-Encoding: 7bit' . "\r\n\r\n";
$message .= 'This is a message with attachments.' . "\r\n\r\n";
foreach ($attachments as $file) {
if (is_file($file)) {
$message .= '--' . $boundary . "\r\n";
$message .= 'Content-Type: application/octet-stream; name="' . basename($file) . '"' . "\r\n";
$message .= 'Content-Disposition: attachment; filename="' . basename($file) . '"' . "\r\n";
$message .= 'Content-Transfer-Encoding: base64' . "\r\n\r\n";
$message .= chunk_split(base64_encode(file_get_contents($file))) . "\r\n\r\n";
}
}
mail('recipient@example.com', 'Subject', $message, $headers);$headers = 'From: foo@example.com' . "\r\n";
$headers .= 'MIME-Version: 1.0' . "\r\n";
$headers .= 'Content-Type: text/html; charset="iso-8859-1"' . "\r\n";
$html = '<html><body><p>This is a HTML message.</p></body></html>';
mail('recipient@example.com', 'Subject', $html, $headers);