mta1.pd.ipreo.com has no MX records.
Question and response
Question
dig mta1.pd.ipreo.com. MX
Answer
The response has no answer records.
Authority
ipreo.com. 900 SOA ns2.ihsmarkit.com. hostmaster.ihsmarkit.com. 2019121230 900 3600 2419200 900
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0