ns-west.cerf.net has no MX records.
Question and response
Question
dig ns-west.cerf.net. MX
Answer
The response has no answer records.
Authority
cerf.net. 3600 SOA ns-west.cerf.net. rm-hostmaster.ems.att.com. 5 3600 1800 604800 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0