Tomasz wrote:

> Gary V schrieb:

> (...)

>>> Is this claim valid? In both cases, you have exactly the same amount of 
>>> mails to filter. In "pre-queue content filtering" you need to have 
>>> enough resources to do the filtering during the connection, it's all a 
>>> function of the amount of emails and the processing power of the 
>>> filtering server...
>> 
>> On a powerful lightly loaded server it can work. On a heavily loaded
>> server it's not practical. Using an after-queue filter allows Postfix
>> to buffer messages.

> Well, every configuration should be made carefully. If you have enough 
> processing power, then I wouldn't say "pre-queue content filtering is 
> the worst of all worlds".

> Now, knowing all pros and cons of "pre-queue content filtering" :) - 
> shall we come back to our topic question, which was: "how to greylist 
> mails that got certain score (5-10) from amavis"?

I would think amavis could only be programmed to do this if it is
configured as a before-queue filter. Using amavis as a before-queue
filter (while beneficial in some cases) is not recommended or
supported so you should probably explore other possibilities.

Selective greylisting has been discussed a few times on the
Postfix list (and this one too). I personally have had good
luck with a patched policyd-weight (that is also patched to use p0f).
The author of policyd-weight is working on incorporating these
concepts into a production version.
http://www.mail-archive.com/[EMAIL PROTECTED]/msg00475.html

The settings for greylisting and p0f need to be found in the file:
my $GREYLIST_RESPONSE = "check_greylist";
my $P0F_ADDRESS = "127.0.0.1"; # only if p0f is used

I personally also set $REJECTLEVEL to 4.5

To use it with Postfix, in main.cf:
smtpd_restriction_classes = check_greylist
check_greylist = check_policy_service inet:127.0.0.1:60000
# that's postgrey

smtpd_recipient_restrictions =
  permit_mynetworks
  permit_sasl_authenticated
  reject_unauth_destination
  reject_unlisted_recipient
  check_client_access hash:/etc/postfix/rbl_client_exceptions
  check_sender_access hash:/etc/postfix/greylist_sender_exceptions
  check_policy_service inet:127.0.0.1:12525
# that's policyd-weight

policyd-weight comes with no init script so one would have to be
created or found.

There are also other ways to do selective greylisting:
http://lists.ee.ethz.ch/postgrey/msg01214.html
http://www.arschkrebs.de/postfix/postfix_greylisting.shtml

Gary V



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