[Mimedefang] return values

[Michael Fox]

Perhaps another couple of newbie questions.  But I'm having some difficulty
understanding the return actions from filter() and filter_multipart() as
they appear in the example
/usr/share/doc/mimedefang/examples/suggested-minimum-filter-for-windows-clie
nts.gz.

Issue 1:  filter and filter_multipart:  return value or not?

/usr/bin/mimedefang.pl does not seem to expect a return value from either
filter() or filter_multipart().

        if (defined(&filter_multipart)) {
            push_status_tag("In filter_multipart routine");
            filter_multipart($in, $fname, $extension, $type);
            pop_status_tag();
        }

        if (defined(&filter)) {
            push_status_tag("In filter routine");
            filter($in, $fname, $extension, $type);
            pop_status_tag();
        }

. yet in the example "suggested-minimum-filter.", sometimes they return
nothing and sometimes they return a true/false value returned from another
function.

    Returns nothing:
        return if message_rejected(); # Avoid unnecessary work

    Returns result of another function:
        return action_accept();

Shouldn't filter() and filter_multipart() simply use "return;" (with no
return value)?  If not, please help me understand.



Issue 2:  bounce or discard, which is it?

In the "suggested-minimum-filter." filter function, there is this:

    # Block message/partial parts
    if (lc($type) eq "message/partial") {
        md_graphdefang_log('message/partial');
        action_bounce("MIME type message/partial not accepted here");
        return action_discard();
    }

I'm confused by the "return action_discard()".  How can it be both bounced
AND discarded?  

Thanks,
Michael