[Evolution] Excluding spam from unread virtual folder

[Nigel Metheringham <Nigel Metheringham dev InTechnology co uk>]

I have a rather bushy tree of imap folders - any of which can be
delivered into directly, spread over a couple of servers.

To make it easier to read through current stuff I use an "Unread"
virtual folder - ie "Status is not Read over all active remote folders".

However this means I get to see all the SpamAssassin tagged spam which
is hitting a couple of explicit spam folders.

Is there a way I can use an expression to either:-
      * Exclude a small number of folders from the ones used as sources
        (listing the ones I want to be included is not an option with a
        couple of hundred folders in total).
      * Exclude messages with an appropriate header setting - ie not
        matching X-Spam-Flag: YES

Cheers
        Nigel.

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[ Nigel Metheringham           Nigel Metheringham InTechnology co uk ]
[ - Comments in this message are my own and not ITO opinion/policy - ]