mx2.alestra.net.mx has no MX records.
Question and response
Question
dig mx2.alestra.net.mx. MX
Answer
The response has no answer records.
Authority
alestra.net.mx. 3600 SOA dns.alestra.net.mx. soporteip.axtel.com.mx. 762215169 10800 3600 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0