auth-ns2.verizonbusiness.com has no MX records.
Question and response
Question
dig auth-ns2.verizonbusiness.com. MX
Answer
The response has no answer records.
Authority
verizonbusiness.com. 300 SOA auth-ns1.verizonbusiness.com. hostmaster.verizonbusiness.com. 37703 600 600 1555200 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0