When I was with #DemonInternet (back when Demon were a competent independent ISP, not a shithole Mikeysoft-as-a-disservice re-seller) I used to quietly research spam, accepting all email for which SMTP delivery was attempted. These days no ISP provides unfiltered delivery, much less SMTP. By comparison I see very little spam, and can't really do much to research it any more. I know why they do it of course - the sheer waste of resource if they didn't. Still disappointing, though.