gate.cotas.com has no MX records.
Question and response
Question
dig gate.cotas.com. MX
Answer
The response has no answer records.
Authority
cotas.com. 3600 SOA calleja.cotas.com. gmorenoc.cotas.com. 2018031053 1800 900 1296000 3600
Additional
. 0 OPT ; payload 4000, xrcode 0, version 0, flags 0