[Evolution] filter in scheme language

[Frédéric Royer <frederic royer obs unige ch>]

Hello,

 I use Ximian evolution 1.0.8 and I'd like to make a filter to flag
mails that contain a certain string many times. 
The only way to do that is a scheme command that should count the
occurences of the string in the message body and flag it if the number
is higher than the threshold. Unfortunately I have no idea in coding
that in scheme.
Can someone give me some help and/or hint ?

 Thanks
 
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