mastercardaemtest.com has no MX records.
Question and response
Question
dig mastercardaemtest.com. MX
Answer
The response has no answer records.
Authority
mastercardaemtest.com. 300 SOA dns2.mastercard.com. hostmaster.mastercard.com. 3 14400 3600 2419200 300
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0