mail.tns3.eu has no MX records.
Question and response
Question
dig mail.tns3.eu. MX
Answer
The response has no answer records.
Authority
tns3.eu. 86400 SOA ns01.cpserver.net. hello.cpserver.net. 2020111006 3600 1800 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0