When spam is detected, the FortiGate unit will deal with it according to the Spam Action setting in the email filter profile. Note that POP3S, IMAPS and SMTPS spam filtering is available only on FortiGate units that support SSL content scanning and inspection. POP3, IMAP, POP3S and IMAPS mail can only be tagged. SMTP and SMTPS mail can be set to Discard or Tagged:
When the spam action is set to Discard, messages detected as spam are deleted. No notification is sent to the sender or recipient.
When the spam action is set to pass, message the spam filter is disabled for this message.
When the spam action is set to Tagged, messages detected as spam are labelled and delivered normally. The text used for the label is set in the Tag Format field and the label is placed in the subject or the message header, as set with the Tag Location option.