lb.yoursrs.com has no MX records.
Question and response
Question
dig lb.yoursrs.com. MX
Answer
The response has no answer records.
Authority
yoursrs.com. 3600 SOA ns1.premiumdns.zone. hostmaster.yoursrs.com. 2026024131 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1400, xrcode 0, version 0, flags 0