relay.skillport.com has no MX records.
Question and response
Question
dig relay.skillport.com. MX
Answer
The response has no answer records.
Authority
skillport.com. 300 SOA bos-gtm01.skillport.com. hostingdomainadministrators.skillsoft.com. 2006161139 3600 1800 1209600 300
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0