Sorry got them around the wrong way, I cannot receive mail and it is POP that is the problem. If my MX records are redirected to my Static IP (yes I do have one) I need a POP server to receive them. I don't need anything special like virtual domains.
I just put in "linuxbox.roamware.com" for the POP host, I assumed that the vm-pop3d process would listen on port 110 for the mail client when it connects. But that does not appear to be happening. It may well be that I need to configure something on vm-pop3d, but the help at
http://www.reedmedia.net/software/virtualmail-pop3d talks about virtual domains mostly and does not explain the basic stuff that newbies like me need.
David