mx3.spamtador.com has no MX records.
Question and response
Question
dig mx3.spamtador.com. MX
Answer
The response has no answer records.
Authority
spamtador.com. 86400 SOA ns7.nsprimario.com. soporte.adw.es. 2026021701 10800 3600 86400 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0