Codice PHP:
$file fopen("export/lista_completa_email.txt""w+" );

while(
$row mysql_fetch_array($result)){
    
fwrite($file$row[email] . "\r\n"); //<== prova con CrLf, non con il solo Lf 
                                                 //      che va bene per unix!
}
fclose($file); 
HTH
Zappa