mta20128.pur3.net has no MX records.
Question and response
Question
dig mta20128.pur3.net. MX
Answer
The response has no answer records.
Authority
pur3.net. 3600 SOA ns0.dnssub.com. hostmaster.pure360.com. 2025102201 10800 1800 1209600 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0