Domínio nao recebe emails do Gmail, Hotmail

Um determinado dominio do servidor nao recebe emails do gmail e hotmail.

""
Technical details of permanent failure:
Google tried to deliver your message, but it
was rejected by the recipient domain. We recommend
contacting the other email provider for further
information about the cause of this error. The error
that the other server returned was: 550 550 5.1.1
<email@dominiodocliente>:
Recipient address rejected: User unknown in virtual mailbox table (state 14).
""

Como resolver isto ?

Olha se fosse para enviar poderias ser DNS reverso... mas como eh para receber deveria receber...