php - 尽管在 header 中发送了 base64，但仍无法识别附件

Question

我在用 php 邮件发送附件时遇到问题。问题是电子邮件似乎已发送并已收到，但未被识别为附件。如果我进入邮件的来源，我可以看到它正在发送 base64 并包含附件名称，所以我很困惑为什么客户端无法识别它。有什么想法吗？

$uid = md5(uniqid(time()));
$headers = "From: ".$from_name." <".$mailto.">\n";
$headers .= "Reply-To: ".$from_mail."\n";
$headers .= "MIME-Version: 1.0\n";
$headers .= "Content-Type: multipart/mixed; boundary=\"".$uid."\"\n";
$headers .= "This is a multi-part message in MIME format.\n";
$headers .= "--".$uid."\n";
$headers .= "Content-type:text/plain\n";
$headers .= "Content-Transfer-Encoding: 8bit\n";
$headers .= $message."\n";

foreach ($_FILES as $file) {
    $name = $file['name'];
    $handle = fopen($file['tmp_name'], "r");
    $content = fread($handle, $file['size']);
    fclose($handle);
    $content = chunk_split(base64_encode($content));

    $headers .= "--{$uid}\n";
    $headers .= "Content-Type: {$file['type']}; name=\"{$name}\"\n";
    $headers .= "Content-Transfer-Encoding: base64\n";
    $headers .= "Content-Disposition: attachment; filename=\"{$name}\"\n";
    $headers .= $content;
}

$headers .= "--{$uid}--";
$mailto = 'myemail@email.com';
return mail($mailto, $subject, $message, $headers, '-f' . $mailto);

Answer 1

问题

您的代码有很多问题:

• 电子邮件 header 必须以 CRLF 结尾。你只有 LF。
• B64 编码的文件和消息被添加到标题中。它们应作为邮件正文发送。
• 每部分的消息头和消息体之间必须有一个额外的CRLF。
• 正文部分必须由以 CRLF 开头的分隔符分隔。

电子邮件语法

这是根据 RFC 2046 的多部分消息体结构的摘录。请特别注意 CRLF。 (BNF 语法，有些简化。)

multipart-body := [preamble CRLF]                  dash-boundary CRLF                  body-part *encapsulation                  close-delimiter                  [CRLF epilogue]dash-boundary := "--" boundarybody-part := MIME-part-headers [CRLF *OCTET]encapsulation := delimiter                 CRLF body-partdelimiter := CRLF dash-boundaryclose-delimiter := delimiter "--"

The code

Your code could look something like this:

$uid = md5(uniqid(time()));
$headers = "From: ".$from_name." <".$mailto.">\r\n";
$headers .= "Reply-To: ".$from_mail."\r\n";
$headers .= "MIME-Version: 1.0\r\n";
$headers .= "Content-Type: multipart/mixed; boundary=\"".$uid."\"\r\n";

$body = "This is a multi-part message in MIME format.\n";
$body .= "--".$uid."\r\n";
$body .= "Content-type:text/plain\r\n";
$body .= "Content-Transfer-Encoding: 8bit\r\n";
$body .= "\r\n";
$body .= $message;

foreach ($_FILES as $file) {
  $name = $file['name'];
  $handle = fopen($file['tmp_name'], "r");
  $content = fread($handle, $file['size']);
  fclose($handle);
  $content = chunk_split(base64_encode($content));

  $body .= "\r\n--{$uid}\r\n";
  $body .= "Content-Type: {$file['type']}; name=\"{$name}\"\r\n";
  $body .= "Content-Transfer-Encoding: base64\r\n";
  $body .= "Content-Disposition: attachment; filename=\"{$name}\"\r\n";
  $body .= "\r\n";
  $body .= $content;
}

$body .= "\r\n--{$uid}--";
$mailto = 'myemail@email.example';
return mail($mailto, $subject, $body, $headers, '-f' . $mailto);

引用资料

• RFC 5322 Internet Message Format
• RFC 2045 (MIME) Part One: Format of Internet Message Bodies
• RFC 2046 (MIME) Part Two: Media Types