spf.hubspot.com has no MX records.
Question and response
Question
dig spf.hubspot.com. MX
Answer
The response has no answer records.
Authority
hubspot.com. 1800 SOA jerry.ns.cloudflare.com. dns.cloudflare.com. 2397293101 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0