dns2.udel.edu has no MX records.
Question and response
Question
dig dns2.udel.edu. MX
Answer
The response has no answer records.
Authority
udel.edu. 600 SOA dns1.udel.edu. hostmaster.udel.edu. 100867 86400 14400 604800 600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0