spf.dynect.net has no MX records.
Question and response
Question
dig spf.dynect.net. MX
Answer
The response has no answer records.
Authority
dynect.net. 1800 SOA ns0.dynamicnetworkservices.net. hostmaster.dyndns.com. 2025111101 10800 1800 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0