exchange.delska.com has no MX records.
Question and response
Question
dig exchange.delska.com. MX
Answer
The response has no answer records.
Authority
delska.com. 1800 SOA nola.ns.cloudflare.com. dns.cloudflare.com. 2396967894 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0