> catch_all:
> driver = redirect
> data = admin@${lookup mysql {SELECT domain FROM domains \
> WHERE type="local" and domain="${domain}" }}
>
> regarding the part "driver = redirect"
> what exactly does it do/mean?
[Somebody please correct me if I'm wrong, as I have not yet tested
this hypothesis...]
What I have learned is that, yes, there are a large number of
built-in "drivers" (i.e., routers, transports, or authenticators). Those
built-in drivers do not need to be defined in the config file because they
are built-in.
When you define your own "driver" (router, transport, or
authenticator) you are basically customizing one of the built-in drivers
by using non-default config file options.
In the common case, when a message comes in, it starts at the
first router in the config file, and then goes through them one-by-one
until it matches the preconditions for that router (Section 3.9). Once
the preconditions are met, it falls into that router, and then (commonly)
would go to a transport. It may also be redirected to another router,
etc. -- see Section 3.8 for the full story. For incoming mail, the
message eventually winds up at a transport.
The transport is what would move it from the Exim queue to the
enduser's mailbox file, or maybe a pipe to procmail. The 'smtp' transport
would relay the message on to a different host (I think).
This system is very easy to understand. I was at first confused
because (a) I didn't realize there were a series of built-in drivers, and
(b) because I could find no list of built-in drivers. What I did not
realize is that the drivers are listed as chapters of the manual... that
is, Chapter 15 is the "accept router" (all routers are drivers), Chapter
26 is the "autoreply transport" (all transports are drivers), etc.
I would have kept on track if Section 3.7 would have said
"There are a large number of built-in drivers (routers, transports, and
authenticators) in Exim. You build your own drivers by specifying which
built-in driver you want to use with the 'driver = ' option, and
customizing that with the particular config options for that driver.
The drivers are listed as chapter titles of this manual."
Of course that's completely obvious now (DOH!), but reading
through it for the first time this was not obvious. The HTML is set up
such that you cannot see the titles of subsequent chapters at the time you
are reading a particular chapter. (And when I'm already stuck at Chapter
3, looking ahead ten or twenty chapters is the last thing I want to
confuse myself with.)
> I presume it redirects or tells the router to redirect.
Yes. It tells it to use the built-in 'redirect' router, see
Chapter 21.
> where does it redirect from and to?
> what tells it where to redirect to?
See Chapter 21, I'm just a n00b (as they say on Counter-Strike).
> I am sure this is pretty basic stuff but the router syntax is just not
> very intuitive to me.
Assuming my interpretation is correct, this is both easy and
powerful. I'm starting to feel about Exim the way I feel about Python...!
:)
--Derek
