mail1.adp.com has no MX records.
Question and response
Question
dig mail1.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