All posts I found on this are more than 2 years old, so I'm recalling the issue:

We are setting certain email header so that our Cyrus mailserver delivers Spam messages to the Junk-folder. In case the customer accidentally deletes this folder, Cyrus creates it again.

To ensure a consistant behaviour, we don't allow our customers to change this setting. So to be able to migrate to Zimbra, we either need

a) a way to specify the target folder during the LMTP delivery which our SMTP server sets according to the header or
b) a global filter rule in Zimbra to do this, which is read only, so that the customers cannot change or misconfigure it.

Btw.: In Cyrus, one specifies a list of folders that will be created during a direct subfolder delivery in case they don't exist, so that a misuse is not possible.