[Mimedefang] variables available for greylisting

[Cormack, Ken]

> Yes, but that's half of the story. Then you have to call my_greylist 
> with proper arguments and check its return status and do something. 
> Better change the return values in my_greylist to something simpler. 
> You'll have to call it for each recipient and decide whether to tempfail 
> or accept, in either case for *all* recipients.
> The arguments can be ($Recipients[index], $Sender, $RelayAddr)

What we're basically looking to do, is this.

If the SA score is >= 15, discard.
If the SA score is >= 10 and < 15, quarantine.
If the SA score is >= 5 and < 10, greylist.
If the SA score is < 5, allow the mail without greylisting.

This way, we toss the stuff that is clearly junk, quarantine the stuff that
is likely to be junk, greylist the stuff that is borderline, and allow clean
stuff to come straight through.

Most of the logic branching based on SA score is already in place.  And
currently, the grelisting logic works fine when called from
filter_recipient.  I'm just interested in knowing whether the elements of
the triplet were still available for me to use, in filter_end.

Ken