cache.qwilt.com has no MX records.
Question and response
Question
dig cache.qwilt.com. MX
Answer
The response has no answer records.
Authority
qwilt.com. 600 SOA pdns07.domaincontrol.com. dns.jomax.net. 2026020600 28800 7200 604800 600
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0