spf05.hubspotemail.net has no MX records.
Question and response
Question
dig spf05.hubspotemail.net. MX
Answer
The response has no answer records.
Authority
spf05.hubspotemail.net. 180 SOA ns10.digicertdns.com. dns.digicertdns.com. 2009010105 43200 3600 1209600 180
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0