MySql:ordenar por y agrupar al combinar sin dar el último registro

¿Cómo puedes GROUP BY id_thread cuando no hay id_thread columna en su tabla?

SELECT * 
FROM contacts 
WHERE id_receiver = 1 
                                 --- GROUP BY id_thread
                                 --- removed 
ORDER BY created DESC
LIMIT 1                          --- only show one row

Según sus comentarios, lo que desea es lo último (ordenado por created ) fila para cada id_thread , que es una consulta diferente y más compleja. Incluso hay una etiqueta para este tipo de consultas, denominada [greatest-n-per-group] .

SELECT c.* 
FROM contacts AS c
  JOIN
    ( SELECT id_thread, MAX(created) AS created 
      FROM contacts 
      WHERE id_receiver = 1  
      GROUP BY id_thread
    ) AS g 
    ON (g.id_thread, g.created) = (c.id_thread, c.created) 
WHERE c.id_receiver = 1