mail01.metrocom.com.pa has no MX records.
Question and response
Question
dig mail01.metrocom.com.pa. MX
Answer
mail01.metrocom.com.pa. 5 CNAME sep.us-east.atmailcloud.com.
Authority
us-east.atmailcloud.com. 900 SOA ns-457.awsdns-57.com. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0