smtp getting down frequently

We have CentOS and WHM on our server.

We are facing issue with smtp that it is getting down frequently from last two weeks.

We have checked the logs but not getting any reasons for downtime of smtp. Also we can not see any IP in SYNC_RECV. Also there is no user who is doing spamming or mass mailing. No one is sending mails from nobody.

Can this be a network issue??

Please suggest any solution.

 

EXIM is getting just dead and we have restart it manually.

This is happening frquently.

 

Hello,

Yes we have chkservd running on our server. Let us tell you the exact situation again.

The SMTP gets down again and again. We don't get the reason till now for this.

Sometimes the SMTP is automatically restarted because of chkservd . Or sometimes we have to manually restart it again.

We are using Nagios for system alert and we get system alert that SMTP is down.

To get the SMTP restarted it not the issue for us now. But we need to find out the reason that why it is getting down. There is no spamming, mass mailing or sending mails from nobody on the server. Also there is no kind of attack on it.

Can this error come from the datacenter? Or from the network ?

Again thanks for all your replies and suggestion.