Normal authors: release book to the public early in the week, with much fanfare.
Me, late Friday afternoon, from a dark alley: "psst! Hey, you! Yeah, you! #sysadmin! Buddy! You ever wanted to Run Your Own Mail Server?" #ryoms
https://www.tiltedwindmillpress.com/product/ryoms-ebook/
(boosts appreciated! )
@mwl
I finaly migrated MX records of my self hosted server to Proton. Glad I did it. Last 2 years was a pain without rDNS from my ISP Provider.
Yeah, you need reverse DNS, period. That's in Chapter 0 of the book.