Those are temporary/ephemeral IP restrictions. They typically last for a few minutes. That's not the same as the static 'outdated' IP block lists that the OP is referring to.

Simply said: if block lists were permanent, we'd be blocking the entire IPv4 space by now. And also, spammers would have almost free reign when using IPv6, since you can get blocks of millions of addresses for free. Large email providers know this, they have been battling spam for decades now.

When enabling DMARC the IP address more or less becomes irrelevant. If the email is not DMARC aligned the email won't be accepted anyway (I'm assuming a 'reject' DMARC policy here) and if the email is DMARC aligned, the domain reputation, rather than IP reputation will be used.

When working with DMARC aligned domains, most email service providers will rely solely on content based spam detection, and how often people flag the email as spam to determine the domain's reputation.

Of course I am generalizing here. What I wrote here is true for most large email service providers, but each have their own implementation. And of course there will always be self-hosted/on-premise solutions that keep using static block lists (for example: Spamhaus).

These aren't temporary. Every message I have sent for years has got the same block message. Sure, they aren't necessarily outdated but they aren't lasting for a few minutes.

> When working with DMARC aligned domains, most email service providers will rely solely on content based spam detection

This seems to be true for most major providers. But my experience shows that Microsoft and Apple don't do this. They still apply strict broad IP-based blocking. Sending messages from the same domain via a relay such as AWS SES is perfectly fine. But if the sender IP is in Digital Ocean ASN it is dropped right away. The domain is p=reject