Milter-greylist

Hello people,

I've just built and installed milter-greylist, and I have a few
ideas/troubles:

1.
Submissions that pass SPF check are not greylisted.  I think that this
is wrong.  Being SPF-clean does not guarantee that the message is not
spam.  There where even reports in press that there was more SPF-clean
spam mesaured than SPF-clen valid mail.  What SPF does guarantee is
that sender domain was not spoofed.

I think that better approach would be to greylist such messages, but
instead of (sender-IP sender-address recipient-address) tuple use
(sender-domain sender-address recipient-address) or maybe rather
(sender-domain recipient-address).

Maybe there could be also a config option to block (with 5xx)
submissions if SPF check returns 'fail' or 'softwail'.

2.
I find it very a compelling idea to have dynamic greylisting delay,
per sender IP (or sender domain for SPF-verified submissions), growing
if there are many submissioons for non-existent users from the IP.
This would be kinda simple reputation system.

3.
Now and then, I get this pair of messages in the log:

Dec  9 00:19:28 auhost sm-mta[14836]: iB8LJHFq014836: Milter
(milter-greylist):
timeout before data read
Dec  9 00:19:28 auhost sm-mta[14836]: iB8LJHFq014836: Milter
(milter-greylist):
to error state

(and sendmail returns "451 4.3.2 Please try again later" because I
configured the filter as "F=T").

Also, from time to time, there is a message:

Dec  9 00:41:07 auhost milter-greylist: smfi_getsymval failed for
{if_addr}

in the log.

Any comments?

Regards
Eugene