Zsolt,
I'm not familar with the SMTP side of courier but I do have a few
standard MTA suggestions:
1.) If possible, create, and maintain(!) a list of hosts you
automatically refuse connections from. This can also be done at the
firewall level. If possible, you might even think of creating a script
that parses your logs, looks for say >50 'bad local parts' coming from
them, and then adds a drop rule to your firewall.
2.) Use, web-based spam helpers like spamhaus, blitzed, spamcop, etc.
These hosts provided DNS lists of known spammers. You can connect this
to your firewall (if it's smart enough), or your SMTP daemon. It will do
a DNS lookup on any host that's trying to connect to it and deny it
mail-sending priviledges if it gets a DNS hit from one of the above
hosts. Again, if you add a nice quick script to parse logs and look for
entries denying hosts based on this reason, and then make firewall
entries you can make it so that these hosts never see your SMTP daemon
ever again. And if courier doesn't support this functionality, then you
can look at your logs manually once a day/week, etc. and add any DNS
hits you get for hosts directly to your firewall manually.
3.) Try rate limiting. It only allows hosts to send or even relay mail
to a certian number of recipients per time period (i.e. 300 per 3hrs),
if they go over that limit, they're automatically blocked. This has the
added benefit of ensuring hosts within your network that get infected
with a spam bot aren't allowed to pollute your network either (assuming
you relay as well as accept for them).
Well that's all I can think of for now. Hope it helps. I don't know
that all (or even any) of these are directly pluggable to the Courier
SMTP though.
Chris
On Fri, 2006-05-26 at 10:33 -0700,
[EMAIL PROTECTED] wrote:
> What do you think of it? Is it possible to
> suspend/decrease the delays in the smtp sessions in courier
> some way if the
> user is unknown? This could speed up message processing and in
> turn decrease
> the delay of good mails.
>
> Thank you very much for your help and time.
>
> Best regards
>
> Zsolt Sandor
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