[danpalmer]

Was it "Return Path"? If so, yes, they are just a racket. They ostensibly provide consulting services on this stuff, but in reality they have a (exclusive?) deal with Microsoft to change scores and allowlist, so you just pay them and they get your email through. Pricing is based on volume of email, I think we were paying $10k/yr for our emails to get to Microsoft hosted addresses.

[petemir]

I cannot 100% confirm it but "Return Path" (now Validity) definitely rings a loud bell :), and the figure is also in the ballpark -- we definitely started to send less e-mails just to be able to afford/test them.

I felt outraged at the moment because it was clearly a "pay-to-play" scheme, but ~8 years ago the number of Hotmail/Outlook addresses in my country was definitely substantial. Probably it still is.