time.cloudflare.com has no MX records.
Question and response
Question
dig time.cloudflare.com. MX
Answer
The response has no answer records.
Authority
time.cloudflare.com. 1800 SOA jobs.ns.cloudflare.com. dns.cloudflare.com. 2397500429 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0