Thanks all for the help, I got the latest spam last night, it gave a return address as a Bigfoot.com customer, I contacted bigfoot abuse team sending them the headers which came with the email.
The headers were false and the return address was forged, I got the info in bigfoot.com reply to my complaint, the webmaster address was also given for me to complain to. I followed the link and ended up on a site to do with US military.
What has been happening has been described above by JinK, in the spam mail the To line: in the headers are variations of my email address, I do not get any other spam except for this particular product, DVD copy software, the site is http://www.abe10.net/dvd/index.html. I can find no way to contact these people as the page is set up for payment details only. The spam does not coincide with any site, it pops up out of the blue.
I used the link in the bigfoot.com reply, http://geektools.com/cgi-bin/proxy.cgi to look up 6.7.014, the result was:
OrgName: DoD Network Information Center
Address: 7990 Science Applications Ct
Address: M/S CV 50
NetRange: 18.104.22.168 - 22.214.171.124
NetType: Direct Allocation
Comment: Army Information Systems Center
Comment: U.S. Army Yuma Proving Ground
Comment: Building 2105
Comment: Yuma, AZ 85365-9110 US
OrgTechName: Network DoD, Network
The ip(?)number is common to all the previous spam, hope this explains the DOD link.
Sorry for such a long post but I felt that since people are kind enough to help I should try to answer their questions best I can.