_spfb.iomart.com has no MX records.
Question and response
Question
dig _spfb.iomart.com. MX
Answer
The response has no answer records.
Authority
iomart.com. 3600 SOA heracles.iomart.com. hostmaster.iomart.com. 2026021903 43200 1800 2419200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0