Regarding the mail content filtering configuration of Huawei USG6000 products, which of the following statements...

Mail filtering will only take effect when the mail filtering configuration file is invoked when the security policy is allowed.

When a POP3 message is detected, if it is judged to be an illegal email, the firewall's response action only supports sending alarm information, and will not block the email o

When an IMAP message is detected, if it is judged to be an illegal email; the firewall's response action only supports sending alarm messages and will not block the email.

The attachment size limit is for a single attachment, not for the total size of all attachments.