pub has no MX records.
Question and response
Question
dig pub. MX
Answer
The response has no answer records.
Authority
pub. 3600 SOA v0n0.nic.pub. hostmaster.donuts.email. 1772023748 7200 900 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0