postfix sbg mail gateway

main.cf
--------------------------------------------------------------
#inet_interfaces = localhost
inet_interfaces = all

#mynetworks_style = host
mynetworks_style = subnet

myhostname = domainku.com
mydomain = domainku.com
mynetworks = 192.168.228.0/28, 127.0.0.0/8
local_recipient_maps =
--------------------------------------------------------------


dengan konfigurasi di atas, jika kirim email dari client
selalu muncul "relay access denied", jika dari server 
lancar.

apalagi yg harus ditambahkan agar postfix dapat
merelay email dari semua client yg ada di local network ?

catatan:
client di local network diperbolehkan memakai sembarang
domain (mail from:) dan ke tujuan domain manapun (rcpt 
to:).

---
ns
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