mail.mrnetgroup.com has no MX records.
Question and response
Question
dig mail.mrnetgroup.com. MX
Answer
The response has no answer records.
Authority
mrnetgroup.com. 10800 SOA ns.mrnetgroup.com. administratoren-websites.nexnet.de. 2026020401 10800 3600 1209600 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0