[jnd-cz]

How recent is your experience? Did you set up TLS, SPF, DKIM, DMARC, DANE/MTA-STS? That's what makes modern mail secure and deliverable (besides basics like matching reverse DNS). The beauty of Mox is that it tells you what exact DNS records you need to set up and it takes care of the certificates. Once it's done I found I have better internet.nl score than some big companies.