Mark here is the option you might want to look at:
serialize_hosts (smtp) option
Option: serialize_hosts
Type: host-list
Default: unset
Because Exim operates in a distributed manner, if several messages for the
same host arrive at around the same time, more than one simultaneous
connection to the remote host can occur. This is not usually a problem
except when there is a slow link between the hosts. In that situation it may
be helpful to restrict Exim to one connection at a time. This can be done by
setting `serialize_hosts' to match the relevant hosts.
Exim implements serialization by means of a hints database in which a record
is written whenever a process connects to one of the restricted hosts, and
deleted when the connection is completed. Obviously there is scope for
records to get left lying around if there is a system or program crash. To
guard against this, Exim ignores any records that are more than six hours
old.
However, if you set up any serialization, you should also arrange to delete
the hints database whenever your system reboots. The names of the files all
start with `serialize-<transport name>' and they are kept in the `spool/db'
directory. There may be one or two files per serialized transport, depending
on the type of DBM in use.
--snip
Later,
Brian
----- Original Message -----
From: "Mark Ivens" <mivens@???>
To: <exim-users@???>
Sent: Friday, September 08, 2000 4:55 AM
Subject: [Exim] inverse of smtp_reserve_hosts
> Can anyone think of a way of limiting the number of SMTP connections
> solely for a given host-list?
>
> We already use smtp_accept_reserve to reserve connections from our own
> servers but I would like to be able to do sort of the opposite as
> well; to limit connections for a list of prefixes to a much lower
> value than the default. Something like smtp_nasty_hosts and
> smtp_nasty_accept_max :-).
>
> The only way I could think of achieving this was by setting
> smtp_reserve_hosts as !nasty_network/24 but this doesn't seem to work.
>
> I was wondering if anyone else had any ideas. It would be really nice
> thing to add to ones armoury for use in those soul destroying
> 4am-pager-goes-off-cos-of-a-spammer moments :-).
>
> --
> ----------------------------------------------------------------------
> Mark Ivens mivens@??? "I'd buy that for a dollar!"
> Systems Administrator Bixby Snyder - Robocop
> ClaraNET UK Ltd 020 7903 3203
> ----------------------------------------------------------------------
>
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