ext.nexinto.com has no MX records.
Question and response
Question
dig ext.nexinto.com. MX
Answer
The response has no answer records.
Authority
ext.nexinto.com. 10 SOA a.prim-ns.de. hostmaster.nexinto.net. 2019022804 28800 7200 604800 10
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0