online has no MX records.
Question and response
Question
dig online. MX
Answer
The response has no answer records.
Authority
online. 900 SOA ns0.centralnic.net. hostmaster.centralnic.net. 1418635 900 1800 6048000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0