虽然有现成的类库（如PEAR）可以很方便地实现附件添加和发送，但是对于一些小站点（服务器硬件、网站规模都不理想），安装PEAR可能会带来不必要的负担，降低WEB程序运行效率。
通过对邮件格式的认识，我们可以写一个脚本来发送附件。代码并不长：
[php]
function mailSend($to, $subject, $message, $attach, $from, $replyto) {//定义边界线$boundary = uniqid();//生成邮件头$header = "From: $fromReply-to:$replytoContent-type: multipart/mixed; boundary="$boundary"";//获取附件文件的MIME类型$mimeType = mime_content_type($attach);//对附件文件进行编码和切分$fp = fopen($attach, "r");if ($fp) {$content = fread($fp, filesize($attach));$content = chunk_split(base64_encode($content));fclose($fp);}else {die("Failed to open file…");}//生成邮件主体$body = "–$boundaryContent-type: text/plain; charset=utf-8;Content-transfer-encoding: 8bit$message–$boundaryContent-Type: $mimeType; name=$attachContent-Disposition: attachment; filename=$attachContent-Transfer-Encoding: base64$content–$boundary–";//发送邮件mail($to, $subject, $body, $header) or die("Failed to send mail…");}[/php]
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