A lot of these emails come out of tententwelvecorp.com. The site has been shut down but there are bots set up to keep sending emails. The worst is getting "joe Jobbed". This is where they use your dot com as the return address but change the prefix to nonsense, like
xyz@pelicanparts.com.
Yes this is illegal but it is hard to enforce, especially when it becomes international. You can complain to the
FTC and send copies of the spam to
spam@uce.gov but it probably will do no good.
Here's a
link to some current discussions on the problem.