spf.drhinternet.net has no MX records.
Question and response
Question
dig spf.drhinternet.net. MX
Answer
The response has no answer records.
Authority
drhinternet.net. 300 SOA ns1.drh.net. root.ns1.drh.net. 2026022301 86400 180 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0