Or in other words is my new #showerthought suspicion that some computers in business or organisation offices are unintentionally part of spam botnets valid or not ?
I can't remember the last time I got a spam email honestly. I changed my address like 5+ years ago and it just stopped and never resumed. It's not the email provider filtering them either, the only thing it catches are legitimate but automated messages.
In an afternoon you can clean up your mail, cancel subscriptions, setup some anonaddy or simplelogin emails for future control, and in the span of a week, you kill the remaining spam emails that come and you'll be mostly free of spam forever (aside from very sporadic junk that will be easily deleted).
Email open rates on the weekend are way way lower than during the week.