ns3-auth.viatel.net has no MX records.
Question and response
Question
dig ns3-auth.viatel.net. MX
Answer
The response has no answer records.
Authority
viatel.net. 600 SOA ns1-auth.viatel.net. hostmaster.viatel.net. 2023100201 10800 900 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0