From: "Eric Thomas" <[log in to unmask]>
>       My experience is that keying
> on the subject is a bad idea as they come in umpteen different languages
:-(

I, too, would prefer keying on the functional components of the message. For
anyone who had trouble finding them, the MIME headers for the attachments
had these characteristics:
    Content-class: urn:content-classes:recallmessage
    Content-class: urn:content-classes:recallreport

Apparently, the recalled message is only identified by subject line. That
(and the name of the recall sender) appear in text in the recallmessage
part, which apparently isn't visible to systems not supporting the
content-class.

Richard Helmke's suggested filters probably have the best dispositions:
REJECT the recallmessage (with a "please don't do that!" notice), and
DISCARD the recallreports.

Hal Keen