Your Startup Is Spam
This is a neat/good idea. I would love to hear if there is a counter argument why NOT to do this, though. However, your current logic makes a lot of sense to me. It's awesome that you (the OP of the article -- if it's not the HN op) could think outside of the box for this great solution.The only argument I could potentially see is that by coming through the provider and not the "sendee" is the "real" mailbox spam filter. Maybe "joe@bob.com" gets marked as spam in the mail client but not if it's from "Google+", etc.