• dns

dns

Domain name service

Check mail record with dig

• dig mx bitarus.allowed.org

Check mail record with dig directly in name server

• dig mx bitarus.allowed.org @ns.bitarus.allowed.org

Check reverse dns

• dig -x 54.68.9.58

Ask for Reverse DNS for EC2 Elastic IP address

• https://portal.aws.amazon.com/gp/aws/html-forms-controller/contactus/ec2-email-limit-rdns-request