spf.flowmailer.net has no MX records.
Question and response
Question
dig spf.flowmailer.net. MX
Answer
The response has no answer records.
Authority
flowmailer.net. 300 SOA ns1.flowmailer.net. contact.flowmailer.net. 2026021901 3600 300 7200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0