_spf.lists.ozlabs.org has no MX records.
Question and response
Question
dig _spf.lists.ozlabs.org. MX
Answer
The response has no answer records.
Authority
ozlabs.org. 60 SOA ns.ozlabs.org. hostmaster.ozlabs.org. 2025123399 14400 3600 2419200 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0