partner_c_spf.monster.com has no MX records.
Question and response
Question
dig partner_c_spf.monster.com. MX
Answer
The response has no answer records.
Authority
monster.com. 600 SOA ns1.tmpw.net. hostmaster.tmpw.net. 1771743004 1800 600 604800 86400
Additional
The response has no additional records.