You don't own the IP address your EC2 instance uses, even if it's a "static" IP. It will be difficult/impossible to get the reverse DNS (aka PTR aka IN-ADDR.ARP

You don't own the IP address your EC2 instance uses, even if it's a "static" IP. It will be difficult/impossible to get the reverse DNS (aka PTR aka IN-ADDR.ARPA) record set up. But even if you did have a proper PTR, SpamHaus (which Hotmail relies on) blackholes the entire EC2 address space. I can't blame them; I would do the same in their shoes.