spf.userve.net has no MX records.
Question and response
Question
dig spf.userve.net. MX
Answer
The response has no answer records.
Authority
userve.net. 3600 SOA ns.userve.net. hostname.userve.net. 2026012701 3600 600 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0