_ob.jobvite.com has no MX records.
Question and response
Question
dig _ob.jobvite.com. MX
Answer
The response has no answer records.
Authority
jobvite.com. 300 SOA ns-1989.awsdns-56.co.uk. hostmaster.jobvite.com. 2013062506 7200 900 86400 300
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0