In 2025 it’s unacceptable for an email vendor to not accept delivery over both IPv4 and IPv6.
Publicly shaming Amazon on this one. Can’t send you DMARC reports if you don’t accept delivery. IPv4 is broken and they are a huge contributor for why we are out of IPs.
Amazon currently holds over 100 Million public IPv4 addresses with an estimated value of over 2 BILLION dollars just in IP addresses.