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What happens when I mark a message as junk (or not junk)?

When marking a message in the Inbox (or any folder other than Junk) as junk in the Zimbra Web Client, either by right-clicking a message and selecting "Mark as Spam" or by typing "ms", the message is moved to the Junk folder. Conversely, if you mark a message in the Junk folder as not junk, either by right-clicking the message and selecting "Mark as Not Spam" or by typing "ms", the message is moved to the Inbox.

Nothing else happens. We do not run a local anti-spam filter, so Zimbra cannot "learn" from marking a message as junk or not-junk. We have an outside vendor to filter messages and there is no way to further integrate the two systems.