spf1.centralnic.com has no MX records.
Question and response
Question
dig spf1.centralnic.com. MX
Answer
The response has no answer records.
Authority
centralnic.com. 300 SOA ns0.centralnic.net. hostmaster.centralnic.net. 2025011560 3600 1200 6048000 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0