dd26728.kasserver.com has no MX records.
Question and response
Question
dig dd26728.kasserver.com. MX
Answer
The response has no answer records.
Authority
kasserver.com. 7200 SOA ns5.kasserver.com. hostmaster.kasserver.com. 2602251100 28800 7200 1209600 7200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0