INVALIDATE <invalidate> <findstring> <replacestring>
        <invalidate> =
            Tearline : Invalidate tearline ("---").
            Origin   : Invalidate origin (" * Origin: ").
            Seenby   : Invalidate SEEN-BY.

        This is used to invalidate (change) certain control strings in
        quoted text. Use this in conjunction with D'Bridge or other
        software that chokes on control strings in quoted text. As an
        added bonus feature, if the tearline or origin is invalidated
        to a nul string, they will not be quoted at all.

        By default, the following invalidations are used:

        "---"           ->  "-!-"
        " * Origin: "   ->  " ! Origin: "
        "SEEN-BY"       ->  "SEEN!BY"