ca1smtp01.topdesk.net has no MX records.
Question and response
Question
dig ca1smtp01.topdesk.net. MX
Answer
The response has no answer records.
Authority
topdesk.net. 1800 SOA coby.ns.cloudflare.com. dns.cloudflare.com. 2397998700 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0