error al mandar correo con servidor telefónica

Hola, desde el viernes una dirección que utilizamos regularmente nos devuelve los correos con el siguiente error.

¿Pueden ayudarnos a solucionarlo?

Saludos

 

 

-----Mensaje original-----

De: Mail Delivery System [mailto:MAILER-DAEMON@llsb708-a03.servidoresdns.net]

Enviado el: lunes, 01 de julio de 2013 11:34

Para: xxx@xxx.xx

Asunto: Undelivered Mail Returned to Sender

 

This is the mail system at host llsb708-a03.servidoresdns.net.

 

I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below.

 

For further assistance, please send mail to postmaster.

 

If you do so, please include this problem report. You can delete your own text from the attached returned message.

 

                   The mail system

 

<xxx@xxx.xx>: host mx.e.telefonica.net[213.4.149.253] said: 552 5.2.0

    uxaC1l00U0eWQXE02xaD2Z internal error (in reply to end of DATA command)