Problema con cuenta de correo

[Barvarela]

Hola amigos de Forsdelweb, tengo un problema con una cuenta de correo un cliente que lo tengo hospedado en godady (serv. compartido)
Este es el rebote:
553 Dynamic pool 200.31.93.254.
<unblock.secureserver.net/?ip=200.31.93.*>

Este es el reporte de unblock.secureserver.net
We cannot find reverse DNS for this IP.

RDNS converts IP addresses (200.31.93.254) to names (such as mail.example.com). Unconfigured networks are at high risk for spam and virus activity. Please contact your ISP to have RDNS assigned to your IP.

Y esta es la respuesta de soporte de godaddy
Unfortunately, the IP address 200.31.93.* is not eligible for unblocking. This IP address comes from a cable/dsl/dialup pool, or other dynamic IP pool. Connections coming from a pool are nearly impossible to trace back to the originating computer. It is for that very reason that cable/dsl/dialup pools are very commonly used by spammers and virus writers.

Due to the large number of virus-infected personal computers on cable/dsl/dialup connections, we no longer accept mail directly from these sources. Senders in cable/dsl/dialup pools should configure their mail software to send outgoing mail through their ISP's dedicated outgoing mail server. The server is usually named 'smtp.example.com' or 'mail.example.com'. The ISP's support line will be able to give you more details. We have whitelisted the mail server of most major ISPs, so the mail will get through if sent through these systems.

If you have a static IP address for a dedicated mail server, please reply with the specific address. We can then investigate further.

No entiendo por que la IP es ilegible para el desbloqueo, la respuesta simplemente dice que esta infectado el PC en el que esta el hosting?? He hecho otras pruebas con otro mail de ese mismo hosting y dominio y no he tenido problemas, me podrian ayudar, saben de este problema??. Gracias