IP range is one of the mechanisms hMailServer uses for security. Using IP ranges, you can give different access to different computers depending on their IP addresses. For example, you can enable IMAP for your network while people outside the network (e.g. on the Internet), can only access POP3.
Normally, there should be no reason to add or remove IP ranges. You should not do this unless you are sure of what you want and how to achieve it. The default IP ranges created during installation should work for most users.
The steps below describe a way to set up IP ranges for a home network with 3 computers. It is assumed that you have a home network where the computers have been assigned IP addresses starting with 192.168.1.
The above instructions are valid for 5.2 and later.