mta.xq11.com has no MX records.
Question and response
Question
dig mta.xq11.com. MX
Answer
The response has no answer records.
Authority
xq11.com. 900 SOA ns0.isprit2.de. hostmaster.xq11.com. 2015102708 28800 1800 691200 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0