I made a mistake. I've just set up a new NS7 server, and there are a some working email accounts, and it is fine.
But I set the Samba NETBIOS domain name to ZZZKFT, and now I can't reach the ZZZKFT.COM site behind the server.
The FQDN name of the server is mailserver.zzzkft.com.
Is there any way to fix this problem? I can't lose any email.