_spf-b.sumtotalsystems.com has no MX records.
Question and response
Question
dig _spf-b.sumtotalsystems.com. MX
Answer
The response has no answer records.
Authority
sumtotalsystems.com. 300 SOA a1-53.akam.net. hostmaster.sumtotalsystems.com. 2022112783 3600 600 604800 300
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0