The FortiGate unit does not tag spam email when using IMAP

Description

Fortigate spam tag does appear when using IMAP

Mail Clients
& Protocols

• IMAP
• Outlook express 6
• Mozilla Thunderbird 1.0

Explanation

When the client builds its message list, it retrieves envelopes first.  FortiGates do not process these envelopes because they do not contain enough information to make a decision.

During the next step, the client retrieves the message bodies -- it is this content that the FortiGate uses for spam analysis and subject tagging.

Some clients (Outlook express, Mozilla Thunderbird) do not update the message subject when it differs from the IMAP envelope and the body.

Consequently, subjects are not tagged in the email list, though they are tagged in the preview pane.

This is an IMAP client issue.

Note: Outlook 2000 is not affected by this problem.