monitor.vodafone.es has no MX records.
Question and response
Question
dig hhlm6vx.x.incapdns.net. MX
Answer
The response has no answer records.
Authority
x.incapdns.net. 60 SOA ns1.x.incapdns.net. hostmaster.incapsula.com. 5 3600 600 604800 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0