mail2-4.adp.com has no MX records.
Question and response
Question
dig mail2-4.adp.com. MX
Answer
The response has no answer records.
Authority
adp.com. 60 SOA dc01exdnsgm.net.adp.com. hostmaster.adp.com. 2015071396 10800 3600 2592000 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0