I'm sorry this page needs to exist, it's partly my fault. I created the first "large scale" SPF record (for eBay and PayPal), and agreed that this was the best way to do it. I guess the people after me agreed too, because 20 years later it's still pretty much the same shape as when I made it!
But I don't have any regrets, the format was pretty straightforward and offered a lot of flexibility. The biggest issue was the parsing libraries handling all of the "include" statements correctly.
Eh, SPF is one of the few things I don't hate about modern e-mail. Pretty easy to figure out / tweak / parse. I like dealing with it way more than MTA-STS.
MTA-STS really is a drag. Baking in dependencies on a web server and web PKI is a true drag. Such web infrastructure has different operational profiles/modes of resilience that it’s a real impedance mismatch for those who can’t or don’t want to manage a highly-available web server.
But I don't have any regrets, the format was pretty straightforward and offered a lot of flexibility. The biggest issue was the parsing libraries handling all of the "include" statements correctly.