lum.spnr.de has no MX records.
Question and response
Question
dig lum.spnr.de. MX
Answer
The response has no answer records.
Authority
spnr.de. 300 SOA nox.spnr.de. hostmaster.spnr.de. 12975 14400 3600 1209600 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0