If you use a virtual IMail domain with an IP Address , all capabilities of regular IMail Server mail domains are available to virtual domains with IP addresses. The only limitations of virtual IMail domains with IP addresses are:
In Microsoft Windows, this requires the extra step of adding an IP address in the Windows NT TCP/IP configuration in the Control Panel (Network Connections > Local Area Connections > Properties > TCP/IP Protocol > Advanced).
Important: Whether you use a real IP address or a virtual IP address, you need to make the proper DNS entries for your mail domain(s). If you use a virtual IP address, the MX record (in DNS) for the mail domain must point to a real IP address.