exchext.swm.de has no MX records.
Question and response
Question
dig exchext.swm.de. MX
Answer
The response has no answer records.
Authority
swm.de. 60 SOA ns.swm.de. firewalladm.swm.de. 2026021601 3600 7200 604800 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0