ns03.sorbsecurity.com has no MX records.
Question and response
Question
dig ns03.sorbsecurity.com. MX
Answer
The response has no answer records.
Authority
sorbsecurity.com. 60 SOA ns01.sorbsecurity.com. admin.sorbsecurity.com. 2023051801 3600 900 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0