pma1vmlupsmtp02.acquirebpo.com has no MX records.
Question and response
Question
dig pma1vmlupsmtp02.acquirebpo.com. MX
Answer
The response has no answer records.
Authority
acquirebpo.com. 60 SOA ns-1817.awsdns-35.co.uk. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0