modem.beeline.ru has no MX records.
Question and response
Question
dig modem.beeline.ru. MX
Answer
The response has no answer records.
Authority
modem.beeline.ru. 3600 SOA ns1.beeline.ru. admin.bee.vimpelcom.ru. 48 900 600 86400 3600
Additional
. 0 OPT ; payload 4000, xrcode 0, version 0, flags 0