I have a "throwaway" Yahoo account for such purchases since I found out the hard way a long time ago that e-mail addresses are sold by the sales company or used by a sister company on the basis that if you are gullible enough to buy abc software then you may well be gullible to buy xyz software. Gullible might not be the right word here
Other companies I know for sure also sell e-mail addresses to just about every Tom Dick or Harry as well as Mr Scammer!