mx.INFRAMX.RU has no TXT records.
Question and response
Question
dig mx.INFRAMX.RU. TXT
Answer
The response has no answer records.
Authority
INFRAMX.RU. 300 SOA ns5.o7.com. admin.o7.com. 24 600 10800 2419200 600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0