yahoo emails give Unrouteable address

[activa]

hello

all the email going to yahoo are bounced ; and give unrouteable adress error ; the log arethe fallowing :

delivering 1JoNoi-0003Tp-Ru
LOG: MAIN
  ** xxxxxxxx@yahoo.com: Unrouteable address
LOG: MAIN
  <= <> R=1JoNoi-0003Tp-Ru U=mailnull P=local S=2466
delivering 1JoO4N-0004KI-69
LOG: MAIN
  ** nobody@server.xxxxx.com: Unrouteable address
LOG: MAIN
  Frozen (delivery error message)
LOG: MAIN
  Completed

all the other email are sended with no probleme (gmail , hotmail , other domains )

when i make th command

exim -bt xxxxx@yahoo.it the resulkt are fine

xxxxxx@yahoo.it
  router = lookuphost, transport = remote_smtp
  host d.mx.mail.yahoo.com [66.196.82.7]     MX=1
  host f.mx.mail.yahoo.com [68.142.202.247]  MX=1
  host f.mx.mail.yahoo.com [209.191.88.247]  MX=1
  host a.mx.mail.yahoo.com [209.191.118.103] MX=1
  host c.mx.mail.yahoo.com [216.39.53.2]     MX=1
  host c.mx.mail.yahoo.com [216.39.53.3]     MX=1
  host b.mx.mail.yahoo.com [66.196.97.250]   MX=1
  host e.mx.mail.yahoo.com [216.39.53.1]     MX=1
  host g.mx.mail.yahoo.com [206.190.53.191]  MX=1
  host g.mx.mail.yahoo.com [209.191.88.239]  MX=1

anyone has any idea about this error

[activa]

anyone for this ?