I pay close attention to IPv4 addresses for outgoing emails. At work we use several email services and pay for a dedicated IP(v4) at each. And when we provision a new service, we expect our new IP address to be “clean,” by which I mean it is ideally not found on any email reputation list.

For websites and services I don’t care. Some hosting platforms publish via CNAME, and some via A and AAAA records. Most seem to use a mix of v4 and v6 addressing.

The falling price of IPv4 addresses looks to me like we’ve made it to other side of the IPv6 rollout: demand for IPv4 is falling faster than supply now. Not clear if those prices are adjusted for inflation; the post-COVID spike looks like a lot of other nominal price graphs. If not, then the recent price drop is even more dramatic than it appears.

Perhaps in the long run, IPv4 becomes an artisanal choice for uses that depend on stable IP reputation: email sending, primarily. And everyone else relies on TLS for reputation signals, not caring about the IP address.