All email sent into the server fails with the below error, I have serched but cant find a fix, can anyone help please?? my emails been out for over a day - server is ensim 4.0.3

Apr 24 11:53:22 srv02 sm-acceptingconnections[4084]: j3OGrJY6003945: SYSERR(root): mailer virthostmail died with signal 11
Apr 24 11:53:22 srv02 sm-acceptingconnections[4084]: j3OGrJY6003945: smtpquit: mailer virthostmail exited with exit value 75
Apr 24 11:53:22 srv02 sm-acceptingconnections[4084]: j3OGrJY6003945: to=<[email protected]>, delay=00:00:02, xdelay=00:00:01, mailer=virthostmail, pri=48832, relay=domain.com, dsn=4.0.0, stat=Deferred: Connection reset by server.domain.com