VPOP3 needs to run on a computer with a static (fixed) IP address on the 'local network'. This does not mean that it will not work with ISPs that dynamically assign IP addresses!

A computer which has both a LAN adapter AND a dial-up adapter will have two IP addresses: one for the LAN adapter, and one for the dial-up adapter.

The dial-up adapter will have a dynamically IP address assigned by the ISP, and the LAN adapter will have a static IP address assigned by you.

See the VPOP3 help section entitled Preparing your TCP/IP LAN for details on how to assign IP addresses to the computers on your network.