plus has no MX records.
Question and response
Question
dig plus. MX
Answer
The response has no answer records.
Authority
plus. 3600 SOA v0n0.nic.plus. hostmaster.donuts.email. 1772032597 7200 900 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0