fallback.relay.agava.net has no MX records.
Question and response
Question
dig fallback.relay.agava.net. MX
Answer
The response has no answer records.
Authority
agava.net. 10800 SOA ns1.agava.net.ru. hostmaster.ns1.agava.net.ru. 1765233399 14400 3600 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0