that message comes from an IP address that has a reverse dns entry, where the forward dns entry either doesn't match or doesn't exist.
In this case:
Code:
mcd@tsavo:~$ host server1.saneeka.com
server1.saneeka.com does not exist, try again
So, you probably need to find out what the Ip address is, who owns that, and then determine if that IP is a threat.