postfix.yota.com.ni has no MX records.
Question and response
Question
dig postfix.yota.com.ni. MX
Answer
The response has no answer records.
Authority
yota.com.ni. 1800 SOA henry.ns.cloudflare.com. dns.cloudflare.com. 2397363191 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0