Re:I Hit $115k/Month with a Status Quo Improvement
by ransom1538 on Thursday February 21, 2019 @01:17AM
(#19214939)
Following your logic, his idea wouldn't work, and he doesn't make 115k a month. But, clearly, it does [if he isn't lying] - so I am not following.
There's literally _Zero_ value in DNSBL/DKIM/SPF because of this. Email sent from reputable sources is actually _more_ likely to be spam than small mail servers.
Content-based filters are the only thing that work against this sort of spam.