mail.docksmarket.com has no MX records.
Question and response
Question
dig mail.docksmarket.com. MX
Answer
mail.docksmarket.com. 5 CNAME domain-sale-on.sodomains.com.
Authority
sodomains.com. 1800 SOA cris.ns.cloudflare.com. dns.cloudflare.com. 2392786533 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0