System Quarantine Retention Period

Hi,

how could I set system quarantine retention period? I would that Fortimail keep information about viruses filtered at least 30 days. Now after couple of days it cleans folder "Virus" in Quarantine and I do not see what was filtered last time.

In Security->Quarantine->System Quarantine Settings-->Quarantine, where at the bottom is Folders table I have set for Virus folder column "Retention Period Days" value 180 days. But no matter of that Fortimail much often clean System Quarantine Virus folder.

maybe I configured something in wrong way?