I did all of those DNS shnigannas with spf, dmarc and others ones like 6 years ago.

I think I had problems with my emails like 2 twice , with one exchange server of some small recruitment company. I think it was misconfigured.

Ah there were also some problem with gmail at the beginning they banned my domain because I was sending test emails to my own account there. I had to register my domain on their BS email post master tools website and configure my DNS with some key.

In overall I had much more problem with automatic backups, services going down for no reason, IPs being dynamic and etc. Email server just works.