mailbot3.pmacs.upenn.edu has no MX records.
Question and response
Question
dig mailbot3.pmacs.upenn.edu. MX
Answer
The response has no answer records.
Authority
upenn.edu. 600 SOA ipam2.nnn.upenn.edu. hostmaster.upenn.edu. 2002371219 10800 3600 604800 600
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0