Haven't tested, but this should do it.
Suppose your ISP relay host is "mailrelay.example.com" and the user
name and password to use there is "user" and "password" respectively.
Enable SMTP authentication on outbound messages:
Code:
$ postconf -e smtp_sasl_auth_enable=yes
Create a file text file mapping which name/password should be used for
which given outbound destination. This file can contain multiple
lines.
Code:
$ echo mailrelay.example.com user:password > /opt/zimbra/conf/relay_password
Create a postfix lookup table from this text file:
Code:
$ postmap /opt/zimbra/conf/relay_password
Test that the map is okay and that the user: password pair is returned.
Code:
$ postmap -q mailrelay.example.com /opt/zimbra/conf/relay_password
user:password
Make postfix use this:
Code:
$ postconf -e smtp_sasl_password_maps=hash:/opt/zimbra/conf/relay_password
$ postfix reload
reload should do it - in this case no stop/start should be needed.
Also take a look at all the other smtp_sasl config options in
postfix documentation, starting at.
http://www.postfix.org/postconf.5.ht...sl_auth_enable
Beware of smtpd_ vs smtp_ sasl options. For mail being sent out via
SMTP, you care about the latter. smtpd_sasl_* are used for mail client
authentication, and the zimbra install already sets those up.