Ниже приведена функция.
function sendmsg($to, $subject, $text, $from, $file, $type) {
$content = fread(fopen($file,"r"),filesize($file));
$content = chunk_split(base64_encode($content));
$uid = strtoupper(md5(uniqid(time())));
$name = basename($file);
$header = "From: $from\nReply-To: $from\n";
$header .= "MIME-Version: 1.0\n";
$header .= "Content-Type: multipart/mixed; boundary=$uid\n";
$header .= "--$uid\n";
$header .= "Content-Type: text/plain\n";
$header .= "Content-Transfer-Encoding: 8bit\n\n";
$header .= "$text\n";
$header .= "--$uid\n";
$header .= "Content-Type: $type; name=\"$name\"\n";
$header .= "Content-Transfer-Encoding: base64\n";
$header .= "Content-Disposition: attachment; filename=\"$name\"\n\n";
$header .= "$content\n";
$header .= "--$uid--";
mail($to, $subject, "", $header);
return true;
}