>From: Martin Evans <m.d.t.evans@???>
>Subject: [Exim] spam delay trick and smtp_accept_count patch.
>To: exim-users@???
>Date: Mon, 02 Feb 2004 11:47:31 +0000
>
>An anti-spam trick was suggested to me a few weeks ago by a colleague in
>our university. The idea is that we add longish delays into the smtp
>conversation if we suspect that the sender is a spammer. i.e. if the
>sender is on an RBL list we add an acl like:
>
>accept dnslists = rbl-plus.mail-abuse.ja.net
> delay = 1m
>
>My colleague has reported that this trick is successful at reducing the
>amount of spam he sees being delivered into his department.
>
>However, I am concerned that my process tables will fill up with RBL'ed
>hosts connecting to my server and filling up my (smtp_accept_max)
>connections. So, I'd like to defer RBL'ed hosts at a lower limit (to get
>rid of their connections). A one line patch makes the number of
>connections available in the ACLs. Note patch is against exim-4.14 (or
>maybe 4-20):
Why not just use smtp_accept_max_per_host? It's an expandable
string if you want to get creative. This main configuration
variable was there in exim3, so it's always been usable in exim4.
