ns2.uni-bielefeld.de has no MX records.
Question and response
Question
dig ns2.uni-bielefeld.de. MX
Answer
The response has no answer records.
Authority
uni-bielefeld.de. 3540 SOA ns1.uni-bielefeld.de. hostmaster.uni-bielefeld.de. 791434656 10800 1800 2419200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0