mm.mts.rs has no MX records.
Question and response
Question
dig mm.mts.rs. MX
Answer
The response has no answer records.
Authority
mts.rs. 3600 SOA ns1.telekom.rs. hostmaster.telekom.rs. 2026022332 7200 600 1209600 3600
Additional
. 0 OPT ; payload 4000, xrcode 0, version 0, flags 0