colo.transip.net has no MX records.
Question and response
Question
dig colo.transip.net. MX
Answer
The response has no answer records.
Authority
colo.transip.net. 300 SOA ptr0.transip.nl. hostmaster.transip.nl. 2016091902 300 60 604800 300
Additional
. 0 OPT ; payload 1680, xrcode 0, version 0, flags 0