mail.thatssuspicious.com has no MX records.
Question and response
Question
dig mail.thatssuspicious.com. MX
Answer
The response has no answer records.
Authority
thatssuspicious.com. 3600 SOA dns.thatssuspicious.com. hostmaster.thatssuspicious.com. 1342368354 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0