mail-sender.ott.volia.com has no MX records.
Question and response
Question
dig mail-sender.ott.volia.com. MX
Answer
The response has no answer records.
Authority
ott.volia.com. 1800 SOA ns1.volia.net. hostmaster.volia.com. 2025121900 43200 3600 1814400 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0