prova così:
Codice PHP:
<?
session_start();
include("auth.php");
$header="";
$msg="";
$boundary='--' . md5( uniqid("myboundary") );
$ctencoding="8bit";
$subject="Invio allegato da parte di $nickname";
$body="In allegato il documento. $tipooperazione foto in profilo di $nickname. inserimento = $inserimento. modifica = $modifica. cancella = $cancella";
$to="salvatore1610@alice.it";
$from=$_POST['email'];
$ctype="application/x-unknown-content-type";
$basename=$_FILES['all']['tmp_name'];
$name=$_FILES['all']['name'];

$header.="From: $from\nX-Priority: 3\nTo: $to\n";
$header.="Mime-Version: 1.0\nContent-Type: multipart/mixed;\n boundary=\"$boundary\"\n";
$header.="Content-Transfer-Encoding: 8bit\n";

   $msg .="This is a multi-part message in MIME format.\n--$boundary\n";
   $msg .= "Content-Type: text/plain; charset=iso-8859-9\n";
   $msg .= "Content-Transfer-Encoding: 8bit\n\n" . $body ."\n";
   
   $msg .="--$boundary\nContent-type: $ctype;\n name=\"$name\"\n";
   $msg .="Content-Transfer-Encoding: base64\nContent-Disposition: attachment\n  filename=\"$name\"\n";
       $linesz= filesize( $basename)+1;
       $fp= fopen( $basename, 'r' );
       $content = chunk_split(base64_encode(fread( $fp, $linesz)));
       fclose($fp);
   $msg .=    chr(13) . chr(10).$content;

$result = @mail($to,$subject,$msg."\n",$header);
?>