[Mimedefang] greylisting in filter_end after SA check?

[Cahya Wirawan]

Currently I use greylisting in filter_begin with 4 minutes
block time, it works fine and reduce most of the spams. But there
are still few spams slip through with the score between 3 and 6 
(my score threshold is 6) . My idea is to reply the sender a temporary
failure message if the score is between 3 and 6 and set the block time 
to an hour, with the hope if the spam come again later in an hour or
longer, I will have already more information from rbl,razor,dcc or so.
With this selected longer block time, only hard detected spam or 
new triple for legitimate email that look like spam will be delayed 
for an hour, but new triples with easy detected legitimate email will have
only 4 minutes block time. 
So the question is if someone else is doing this additional block time
for specific score and if it is worth to do it (hard detected spam get 
more score after an hour?) . and another question is if it is ok
to send temporary failure massage in filter_end (I think this is ok, 
isn't it? I just want to be sure :) )

thanks,
cahya.