[exim] Re: [CLUG-tech] moving to exim

Let me explain the exim3 notion, and then I will say what changed in exim4.

Exim3 has the concept of three things, routers, directors and
transports. A transport defines how a message gets from one point to
another, so that includes things like smtp and/or uucp. A router
defines how non-local mail is delivered, and a director defines how
local mail is delivered.

So on receipt of a message exim first decides if it is meant for a local
user or a remote address.

If it is meant for a remote address, the message is passed to each
router in turn until one accepts it. The router usually defines what to
do with it, and will also specify a transport to send it over.

If it is meant for a local address, it is passed to each director until
one accepts it. The same sort of philosophy applies here.

If none of the directors (or routers) accepts the message, an error is
returned saying it could not be delivered.

Now in exim4 two things changed, or at least, two things I know of.
Firstly, there is now ACL's, which allows you to deny or allow messages
based on many things. If you apply the exiscan patch, you get aditional
ACL's that allows you to wire in spamassassin or clamav or any other
scanner. The second thing that changed is that the distinction between
routers and directors sort of blurred. There are no directors anymore,
just a sort of seperator (no_more) in the conf file that specifies where
the remote routers end and the others (formerly called directors) begin.

At this point I'm going to have to point you to the exim docs. There is
a chapter that explains how exim delivers mail. They essentially tell
you the same stuff I just did.

Except for the routers, transports and acl's, there are also a whole
bunch of other configuration stuff that belongs in the main
configuration section. These include things like whether it should
check the header syntax, which domains are to be considered local, who
should be allowed to relay, and so on and so forth. The whole file is
split into sections and you just have to add the right configuration to
the right section.

regards,
Izak

Brent Clark wrote:
> Hi all
>
> For my new company I have just joined.
> Ive decided remove M$ exchange to make the plunge and use Exim4 (used to use
> Qmail at previous co).
>
> Would anyone please be so kind as to maybe point to some examples, or links
> (not exim.org) etc.
>
> An kind of assistants would be greatly be appreciated.
> I am totally clueless about Exim.
>
> Could someone please give a lamens term for the definitions of the routers,
> transporters etc.
>
> I plan to use Maildir for my users.
>
> Kind Regards
> Brent Clark
>