ia.colt.net has no MX records.
Question and response
Question
dig ia.colt.net. MX
Answer
The response has no answer records.
Authority
ia.colt.net. 10800 SOA ns20.colt.net. hostmaster.colt.net. 2013209524 3600 1800 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0