www.questionmark.com has no MX records.
Question and response
Question
dig www.questionmark.com. MX
Answer
The response has no answer records.
Authority
questionmark.com. 3600 SOA ns1-02.azure-dns.com. hostmaster.questionmark.com. 2005091286 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0