Description
The article describes how the MIME tag works for email traffic.
Solution
Config snip on FortiGate:
# config emailfilter profile
edit "default"
config imap
set action tag
set tag-msg "SpamByFGT:IMAP"
end
config pop3
set action tag
set tag-msg "SpamByFGT:POP3"
end
next
end
Below is an example of an email header tagged as spam over IMAP protocol.
Date: Mon, 19 Sep 2022 22:23:33 -0700
Subject: Proxy mode inspection issue
From: User2 <u2@forti.lab>
To: u1@forti.lab
Message-ID: <20220919222333.28JMNXBJ001863@forti.lab>
MIME-Version: 1.0
Content-Type: text/html; charset=utf-8
SpamByFGT: =?utf-8?Q?IMAP?=
<p style="margin-block: 0px;">Proxy is not working</p>
Tag to MIME header does not modify the email contents[Subject/Body] directly for a user, rather the email client[Outlook/Thunderbird/etc] can take action based on this inserted Header/Attribute.
