From Zimbra :: Wiki

How would you authenticate two different relay hosts. That is if you use different relayhosts depending on what network you are logged on to, how do you set up authenticate for each.

Is all of this over written with each update/upgrade of Zimbra - ie. do you need to repeat all of these steps each time you upgrade?

Will Zimbra ever incorporate SMTP outbound authentication to a smarthost in the management interface so it is persistent across upgrades? Almost all US ISP's now require SMTP authentication on their outbound SMTP relays.

This is http://bugzilla.zimbra.com/show_bug.cgi?id=4963 - go vote for that bug if you want this feature.

from ericrost

The cname_overrides_server_name section disagrees with the statement in the overview indicating to use the canonical server name, we need to resolve this discrepancy.

This helped me a great deal for configuring Zimbra to an externat smtp that requires ssl:

http://forum.webfaction.com/viewtopic.php?id=1099

Maybe include it in the main atricle?