To start you need to enable SMTP authentication on outbound messages: $
postconf -e smtp_sasl_auth_enable=yes
Next is to create a text file mapping which name/password should be used
for each given outbound destination:
$ echo mailrelay.example.com usernameassword >
opt/zimbra/conf/relay_password this is one line
Create a postfix lookup table
$ postmap /opt/zimbra/conf/relay_password
Test that the map is okay
$ postmap -q mailrelay.example.com /opt/zimbra/conf/relay_password
that should return usernameassword if done right
Make postfix use the above
$ postconf -e smtp_sasl_password_maps=hash:/opt/zimbra/conf/relay_password
Almost done. Two more changes to postfix and then we can send mail
externally. We need to change the port we listen on. This is most
important for people who use an ISP that does not allow the use of port 25
to listen to ( [i]this is most important for Rogers customers in Canada)
postconf -e relay_host=relayhost.yourisp.com:465
Your ISP might want you to use another port, so check with your ISP for an
alternate port.
Restart postfix by entering this
postfix reload