Can't migrate Classic Elastic IP with Reverse DNS to VPC Elastic IP

Thanks, though the issue in this case is that Amazon assign the reverse DNS (PTR) entry as part of removing the restriction on the EC2 instance sending emails (see https://aws.amazon.com/premiumsupport/knowledge-center/ec2-port-25-throttle/)

In the end I solved it by using the form listed in that article and filling it in asking the Amazon team to remove the PTR record, or assign a PTR record for a new VPC-scope Elastic IP address we created. They seem to have done the latter, so I just need to fill the form in again to ask them to remove the PTR record from the Classic-scope Elastic IP address which will then allow me to release it.