one day my ox server stopped receiving mail, it can send but not receive i put the command mailq and gives this

(Host or domain name not found. Name service error for type=A: Host not found, try again)

5568E4F051E 7487 Tue Mar 25 15:17:01
(mail transport unavailable)
my host is something like and it is resolving to

somebody know about this and how to resolve?