adns4.doit.wisc.edu has no MX records.
Question and response
Question
dig adns4.doit.wisc.edu. MX
Answer
The response has no answer records.
Authority
doit.wisc.edu. 600 SOA adns1.doit.wisc.edu. hostmaster.doit.wisc.edu. 14574 7200 1800 3628800 600
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0