ips.as135555.net has no MX records.
Question and response
Question
dig ips.as135555.net. MX
Answer
The response has no answer records.
Authority
ips.as135555.net. 86400 SOA ns1.cityc.support.ips.as135555.net. root.ips.as135555.net. 1 3600 900 604800 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0