The problem exists in all Plesk versions we have, which is Plesk8, Plesk9, Plesk10 (we haven't tested it in Plesk 10.4) for windows and for linux. When we add an ipv4 PTR Record in a server, it allows to use a subnet mask from a drop down menu with values 8, 16, and 24. There is no value 32. So, if we select value 24 for PTR subnet, plesk creates zone: xxx.xxx.xxx.in-addr.arpa For example, if server's IP is 192.168.1.10 it creates zone: 1.168.192.in-addr.arpa which is the C class 192.168.1.xxx The problem that is caused is that if another server from the same C class, with IP 192.168.1.20 for example, sends an email to server 192.168.1.10, then server 192.168.1.10 looks in it's local 1.168.192.in-addr.arpa file (because it is supposed to be for the whole C class). As you may assume, it does not find any PTR record for IP 192.168.1.20, so there are problems with receiving emails from servers in the same C class. Is there any way to make plesk adding PTR with subnet 32 (in the above example, zone file should be 10.1.168.192.in-addr.arpa)?