mm.isdg.com.au has no MX records.
Question and response
Question
dig mm.isdg.com.au. MX
Answer
The response has no answer records.
Authority
isdg.com.au. 10800 SOA isdg.com.au. admin.isdg.com.au. 2024071601 3600 900 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0