Wenn ich die Tabellen der Datenbank kennen würde, hätte ich dir meine Query angepasst...aber vielleicht schaffst du das ja auch alleine 
PHP-Code:
$sql1 = sql_query("SELECT
p.*,
g.k_code AS mail_ist_gebucht,
b.k_code AS mail_in_blackliste,
r.k_code AS mail_in_reload
FROM " . $prefix . "_pwc_paidmails AS p
LEFT JOIN " . $prefix . "_pwc_paidmails_gebucht AS g
ON (p.k_code = g.k_code)
LEFT JOIN " . $prefix . "_pwc_paidmails_blackliste AS b
ON (p.k_code = b.k_code)
LEFT JOIN " . $prefix . "_pwc_paidmails_reload AS r
ON (p.k_code = r.k_code)
WHERE p.k_sponsor = '" . intval($n_id) . "'
AND p.k_art = '" . intval($k_art) . "'
GROUP BY p.k_code
ORDER BY p.k_ver DESC");