ns2.impervasecuredns.net has no MX records.
Question and response
Question
dig ns2.impervasecuredns.net. MX
Answer
The response has no answer records.
Authority
impervasecuredns.net. 14400 SOA ns1.impervasecuredns.net. hostmaster.incapsula.com. 1001 3600 600 604800 300
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0