static.optonline.net has no MX records.
Question and response
Question
dig static.optonline.net. MX
Answer
The response has no answer records.
Authority
static.optonline.net. 900 SOA authns1.cv.net. hostmaster.cv.net. 2012100538 7200 600 604800 900
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0