world has no MX records.
Question and response
Question
dig world. MX
Answer
The response has no answer records.
Authority
world. 3600 SOA v0n0.nic.world. hostmaster.donuts.email. 1772300507 7200 900 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0