smtpaz01.aztecaservicios.com has no MX records.
Question and response
Question
dig smtpaz01.aztecaservicios.com. MX
Answer
The response has no answer records.
Authority
aztecaservicios.com. 900 SOA ns3.aztecaservicios.mx. admindomains.aztecaservicios.com. 2008082001 10800 3600 2419200 900
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0