If find it silly that someone can defend spam as a legitimate "business". Spam is always undesired and must die. In general all advertising over email is just noise.
I had a list for people who read my books and want to get early previews of new material - kind of insiders view into new thinking, more an irregular newsletter than any form of advertising. every single person manually subscribed to the list, there was never any spam, but e-mail open rates on the list have been dropping over the last few years to the point that I stopped sending it out last year. Of course, content might be at fault, but the engagement among the group that opened the e-mail was still good, so I guess this was collateral damage of the general trend in fighting circular e-mail.
I read an article in HBR a few months ago that people mostly now get notifications on mobile devices, so the logical step for promotional marketing (soft spam) would I guess be to move to mobile apps. the stuff that I was sending out wasn't really suited for that, but if I started the whole thing again I'd probably do it with a mobile app.
