In the case of a very new spam, phishing, or virus attack, it may take some time for sufficient user feedback to accumulate in order to begin automatically blocking the attach. For this reason, it is advantageous to rescan mailboxes in order to take advantage of the latest user feedback. CSE provides an option to schedule an automatic rescan of all mailboxes on a server.
How to configure automatic mailbox rescanning
Open the Server Configuration window.
Click the Rescan tab.
Select “Enable scheduled rescanning of messages”.
Select the maximum age of messages to rescan.
The default age is 12 hours. This is usually sufficient to rescan all messages received during inactive periods, such as overnight.