收件人无法打开从数据库发送电子邮件附件的附件，

Question

以前我应该使用确切的文件名和文件类型，我能够发送电子邮件并能够打开文件。但是，如果我从数据库中获取文件的名称，我可以发送包含正确文件名（和类型）但无法打开文件的文档的电子邮件。

        $to = "$email"; //Recipient Email Address
        $subject = "$subject"; //Email Subject
        $headers = "From: example@example.com\r\nReply-To: example@example.com";
        $random_hash = md5(date('r', time()));
        $headers .= "\r\nContent-Type: multipart/mixed; boundary=\"PHP-mixed-" . $random_hash . "\"";

        $attachment = chunk_split(base64_encode(file_get_contents('resume/$fileName'))); // Set your file path here
//define the body of the message.

        $message = "--PHP-mixed-$random_hash\r\n" . "Content-Type: multipart/alternative; boundary=\"PHP-alt-$random_hash\"\r\n\r\n";
        $message .= "--PHP-alt-$random_hash\r\n" . "Content-Type: text/plain; charset=\"iso-8859-1\"\r\n" . "Content-Transfer-Encoding: 7bit\r\n\r\n";

//Insert the html message.
        $message .= $content;
        $message .="\r\n\r\n--PHP-alt-$random_hash--\r\n\r\n";

//include attachment
        $message .= "--PHP-mixed-$random_hash\r\n" . "Content-Type: application/zip; name=\"$fileName\"\r\n" . "Content-Transfer-Encoding: base64\r\n" . "Content-Disposition: attachment\r\n\r\n";
        $message .= $attachment;
        $message .= "/r/n--PHP-mixed-$random_hash--";

//send the email
        mail($to, $subject, $message, $headers);

$ fileName是从数据库获取文件名的变量。