Re: [Exim] Problems configuring Exim 4.10 routers.

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Author: Philip Hazel
Date:  
To: jgolden
CC: exim-users
Subject: Re: [Exim] Problems configuring Exim 4.10 routers.
Joe,

Looks like my suggestion that people on the list might answer hasn't
produced any public responses. Let me see if I can add anything to the
hasty message I sent you before the weekend.

On Mon, 29 Jul 2002 jgolden@??? wrote:

> Server A (exim MTA) Server B (UNIX mail host) and Server C
> (Lotus Notes).
> I want to set up Server A as my main MTA, receiving and
> transmitting mail from and to the outside world. Server A should
> then route to Server B for any UNIX local mailboxes, and Server C
> for other local mailboxes.


OK, so the first question is: How can server A tell whether a given
address has a UNIX local mailbox or not? Do the UNIX users have accounts
on server A? If so, you can use the check_local_user router option to
identify them. If the UNIX users do not have accounts on server A, then
you must consider how server A is to know which addresses correspond to
accounts on server B. The most efficient way would be for a list of
local parts to be regularly generated from the password data on server B
and passed to server A, and put into a cdb (or other indexed) file.
However, if you are using some kind of shared database (one of the SQL
ones, or LDAP) then maybe server A can interrogate this to check the
local parts. Exim has a lot of flexibility in the data it can consult.

The basic structure of the configuration on server A would be something
like this:

ROUTERS
-------

dnslookup:
<the standard dnslookup router to handle non-local domains>

# So now we know that any addresses arriving here are local

unix_users:
driver = accept
<the condition that tests for a UNIX user>
transport = to_server_b

lotus_users:
driver = accept
transport = to_server_c


TRANSPORTS
----------

to_server_b:
driver = smtp
hosts = server.b.host.name

to_server_c:
driver = smtp
hosts = server.c.host.name



One problem with this setup is that it won't reject unknown local
mailboxes, so you might get stuck with undeliverable stuff. If you can
test for valid Lotus users in the lotus_users router, you can avoid
this. Again, if you have everything in some database, that might be
possible.

HTH,
Philip

--
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.