On Wed, 18 Mar 1998, Georg v.Zezschwitz wrote:
> I assume you have even more domains than we have (300-500?).
>
> Our primary decision to use Exim was dued to that Philip included the
> option "relay_domains_include_local_mx". This makes Exim relaying
> everything that has an MX to your machine.
yes, we use this on our relays, which due to histe^Horical reasons were
also used as MX backups. long term, we aim to have entirely separate machines
for incoming (MX) and outgoing (relay)... but its a matter of cost and time!
> As spammers will not be able to set an MX for e.g. AOL to your
> machine, they will not be able to relay to AOL via your machine.
some spammers are becoming pretty sophisticated, and have some surprising
methods for attacking relays (some even abuse BGB at a peering level for
fooling ISPs into accepting traffic).
thus, since PSI hasn't always had the best reputation for keeping its machines
closed to spammer (we always deal with customers who we catch spamming), we
want to be 100% sure that our backup MXs are pretty watertight.
the problem with relay_domains_include_local_mx is that when customers join,
it can take a while for DNS to propagate and occasionally we get problems
with mail bouncing for a few hours until it settles.
> However, some poor people might use your machine as MX-Fallback
> without notifying you.
yup!
> But the great advantage is, that you have a real auto-configuration
> of the relay-domains. A lot of trouble occurs because people don't
> manage to synchronize two different files - the zone-file and
> the relay-domain files.
well, that's another interesting problem!!!
thanks!
Paul
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