WHM dont send the system mails

[manokiss]

hi guys, something strange is hapening here, since 2 days i dont receive the system mails from 2 servers, i checked into &edit setup& section in WHM and the server contact address is there, i tryed changing that address too, but nothing, i dont receive the mails from the system.
2 days ago all was work ok, and i didnt touched nothing, and hapen with 2 servers with cpanel box build 116S, and each server is in different datacenters.

any idea what can be the problem ?

Thanks in advance