_spf.btbpo.net has no MX records.
Question and response
Question
dig _spf.btbpo.net. MX
Answer
The response has no answer records.
Authority
btbpo.net. 1800 SOA dns1.p08.nsone.net. domains.bottomline.com. 1646648819 3600 600 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0