spf1.myworkday.com has no MX records.
Question and response
Question
dig spf1.myworkday.com. MX
Answer
The response has no answer records.
Authority
myworkday.com. 60 SOA dns1.p01.nsone.net. noc.workday.com. 3722 60 60 1209600 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0