In ZCS 5.0.1 and earlier, user filters were run before the spam filter check was run. This meant that if the user filtered mail into a folder, spam would not be identified and sent to the Junk folder.
Beginning with 5.0.2, spam check is completed first and messages identified as spam are moved to the Junk folder. With this change, users cannot write a filter to move false positive spam out of the Junk folder.
Two options:
A) If you prefer ZCS 5.0.2+ to use the spam filter function as it works for 5.0.1 and earlier, you can set the zimbraSpamApplyUserFilters option to True.
This can be done by COS:
zmprov mc COSname zimbraSpamApplyUserFilters TRUE
or for individual accounts:
zmprov ma
user@domain.com zimbraSpamApplyUserFilters TRUE
B) You can create a spam white list for individual accounts that allows an account to identify email addresses that should not be marked as spam: zmprov ma
user@domain.com +amavisWhiteListSender
someone@example.com
RFE to bring this into the end-user UI:
Bug 6953 - Per user white & black lists in the UI