mail.service-now.com has no MX records.
Question and response
Question
dig mail.service-now.com. MX
Answer
The response has no answer records.
Authority
mail.service-now.com. 60 SOA edns140.ultradns.com. root.service-now.com. 31 900 1800 31536000 60
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0