smtp3-0.mailmailmail.net has no MX records.
Question and response
Question
dig smtp3-0.mailmailmail.net. MX
Answer
The response has no answer records.
Authority
mailmailmail.net. 3600 SOA ns1.hyp.net. hostmaster.domeneshop.no. 1771073499 14400 3600 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0