The following commands are incorrect:
Code:
dig mail.greenexample.com any
dig mail.greenexample.com mx
You're using the FQDN of the server not the Domain name, the correct format should be:
Code:
dig greenexample.com any
dig greenexample.com mx
which I suspect won't give you an MX or A record. You need create a dmain with the correct domain name of: dig greenexample.com and add the A & MX record to that.