ns2.gst.net.id has no MX records.
Question and response
Question
dig ns2.gst.net.id. MX
Answer
The response has no answer records.
Authority
ns2.gst.net.id. 86400 SOA ns1.gst.net.id. info.centos-webpanel.com. 2013071600 86400 7200 3600000 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0