When you use a third-party application to filter messages for spam before messages are received by ZCS, the ZCS global rule is to send all messages that are marked by the third-party as spam to the junk folder. This includes messages that are identified as spam and also identified as whitelisted
If you do not want messages that are identified as whitelisted to be sent to the junk folder, you can configure
zimbraSpamWhitelistHeader and
zimbraSpamWhitelistHeaderValue to pass these messages to the user’s mailbox. This global rule is not related to the Zimbra MTA spam filtering rules. Messages are still passed through a user’s filter rules.
