Code:
Sep 29 14:14:39 logical amavis[8072]: (08072-03) extra modules loaded: Net/LDAP/Bind.pm
Sep 29 14:14:39 logical amavis[8072]: (08072-03) load: 0 %, total idle 5856.599 s, busy 1.167 s
Sep 29 14:14:39 logical postfix/qmgr[21296]: F17D2B186DE: removed
Sep 29 14:14:39 logical postfix/lmtp[22626]: 62E30B186E0: to=, relay=none, delay=0,
status=deferred (connect to logical.com.au[202.142.35.233]: Connection refused)
It looks like, after the amavis scan, postfix is attempting to hand the mail back to your public mailserver's IP. Via the admin console, mta tab, turn off DNS lookups on this server, and that should solve the problem for incoming mail. (You'll also want to set a relay_host, for outgoing mail delivery)