asutosh gopinath wrote:
> Hi,
>
> I want to run exim4 in more than one machines in following
> manner:
>
>
> MTA-1 * * * * * * MTA-2 * * MTA-3 * *
> MTA-4 * * * * * * *
> MTA-5 * MTA-6
>
> User of MTA5 wants to send mail to user of MTA1. MTA5 can do
> it directly or can ask any one of the intermediate MTAs to
> pass on the mail so that it finally reaches MTA1. Say, for
> example,
>
> MTA-5--> MTA-6---> MTA-3---->MTA-2--->MTA-1 OR MTA-5--->
> MTA-3---->MTA-1
>
> Similar, if user of MTA-1 sends mail to MTA-5.
>
>
> Can this be achieved by Exim4. If yes then how do I configure
> all the MTAs? Do I have to run a DNS (BIND) on each machine?
>
>
> Please help
>
> Thanks Asutosh
>
>
>
Yes but.
Exim will ordinarily send directly to the destination MX if it
resolves and answers, and retry a lower-priority
secondary/tertiary/whatever MX - or the same route later
if/as/when it does not.
Careful DNS crafting only solves part of the complex routing for
the diagram you propose. Crafting the 'relay_to/from', retry and
'fall-back' rules for the Tinker-to-Evers-to-Chance route can
make your life 'interesting' in a frustrating manner.
Unless your network is Aloha packet Radio, RTTY or ARCnet over a
barbed-wire fence (don't laugh - both work), and/or you expect
to run around a million messages a day, this should be more than
slightly overkill. Not needed even for cellphones or
multi-continent hosts.
ONE server can run multiple instances of Exim, but even a single
Exim can have highly flexible behaviour, handling hundreds of
domains, departments, or branch offices with thousands of users
each. Properly set up on either *BSD or Linux, Exim is very hard
to knock down, so ONE backup is all most of us use.
Cambridge and other Universities use Exim and some have written
up their systems on the web. Multicollege/multi-campus
universities are pretty demanding environments, quite often
justifying multiple servers with different primary
functionality, but, IIRC, still *much* simpler, and dramtivally
more smtp-compliant, than your chart.
..or are you migrating off of 'bang-paths'?
;-)
KISS (Keep It Simple, Stupid)
Bill
