doc.etelecom.ru has no MX records.
Question and response
Question
dig doc.etelecom.ru. MX
Answer
The response has no answer records.
Authority
etelecom.ru. 86400 SOA ns.gblnet.ru. noc.etelecom.ru. 2026033863 10800 1200 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0