You are not comparing apples to apples here. You’re talking about setting up MX records vs memorizing an IPv4 address. There is no way that pxtl@random-IPv4-add

You are not comparing apples to apples here. You’re talking about setting up MX records vs memorizing an IPv4 address. There is no way that pxtl@random-IPv4-address is how you’re handling your email. If you can run a server securely on the public internet, you can set up a domain name. To pretend otherwise is a little absurd. Frankly if you can’t set up a domain properly in DNS, you probably can’t successfully manage to forward a port to your server anyway.