SPF (Sender Policy Framework) is an email authentication method designed to detect forging sender addresses during the delivery of the email. With SPF, there is an exhaustive list defined of the server IP addresses that are allowed to send emails for @domain.com addresses.
v=spf1 include:spf1.amazon.com include:spf2.amazon.com include:amazonses.com -all
SPF policy for @amazon.com addresses is defined in
amazonses.com : Transactional Email: AWS SES (Amazon)