lnk.telstra.net has no MX records.
Question and response
Question
dig lnk.telstra.net. MX
Answer
The response has no answer records.
Authority
lnk.telstra.net. 6400 SOA dns0.telstra.net. hostmaster.telstra.net. 2021365058 10800 3600 604800 6400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0