Thank you for your help with this. My boss reminded me that my jobs
wasn't to make exim work exactly like smail, just prove that we could make
our existing apps work. Using your suggestions I was able to make
something that wasn't as simple or pretty as the pathalias driver, but
worked.
Thanks again,
--John
On Mon, 18 Jun 2001, Philip Hazel wrote:
>
> On Mon, 18 Jun 2001, John Jetmore wrote:
>
> > They need to be treated differently, unfortunately. Although you may not
> > need this, let me explain our set up in a bit more detail.
>
> Thinking through this in "Exim mode":
>
> > 1) we have many customer who route their mail through us for virus
> > scanning. I will refer to the generic domain.com. Under our smail set
> > up, none of these domains are considered local.
> >
> > 2) mail is received, and it is matched against a scan_inbound router.
> > This router (pathalias under smail) rewrites the address as
> > 2scan.domain.com and hands it off to a scan_inbound router, which is a
> > pipe that does various things with the message. This is a delivery
> > transport.
>
> Why does it need to rewrite the address? In Exim you could just match
> these domains against a domainlist router, and route them to a transport
> that does the pipe, without rewriting. Is there some reason why the
> address has to be rewritten?
>
> > 3) the program, when it is done with the message, calls /usr/lib/sendmail
> > to re-introduce the message to the queue, still addressed to
> > user@???.
>
> What happens if you received a message from outside addressed to
> user@????
>
> > 4) Now the message is matched and handled by the scan_outbound router
> > (also pathalias). This router statically routes the email to the
> > customer's private email server and also rewrites the domain to
> > scanned.domain.com.
>
> How does it know what server to use if the address is always
> user@???? I can't see how it distinguishes between
> different original domains. Something is missing here (may be my
> understanding).
>
> > Those are the steps I need to replicate in exim. I need the upmost in
> > flexibility, also, because, for instance, in step four above, some of our
> > customers have the domain rewritten back to just domain.com. If at all
> > possible, I would also like to avoid having to include a transport and
> > router for each domain.
>
> The way most people do virus scanning on Exim is to make use of the
> "received protocol" field. That can be set (using -oMr) by a trusted
> caller. They set up an Exim configuration that passes all messages (or
> those to a specific domain(set)) to the scanner unless the received
> protocol is "scanned-ok". The scanner is permitted to pass them back
> with that particular setting. Thus, no rewriting of any addresses is
> involved. All you need is a first router which says, in effect,
>
> If domain matches xxx and received-protocol is not scanned-ok, route
> to such-and-such-a-transport.
>
> You can use the "domains" and "condition" options to do this. (Or match
> the domains in a domainlist route_list pattern.) The transport sets up
> the pipe.
>
> If you were to adopt such an approach, then rewriting certain
> domains xxx.domain.com to just domain.com after scanning is a
> rewriting issue, not a routing issue. Exim's rewriting rules should be
> able to handle that.
>
> [I'm beginning to suspect that this problem is a conflation of rewriting
> and routing - things which I feel ought to be entirely separate. There's
> a history of people using rewriting for routing - starting with Sendmail
> - and my feeling is that is just confuses things.]
>
> If this doesn't help enough, send me a real example with some real
> domain names off the list (I suspect I'm not quite understanding how
> your names work) and I'll generate more details.
>
> --
> Philip Hazel University of Cambridge Computing Service,
> ph10@??? Cambridge, England. Phone: +44 1223 334714.
>
>
> --
> ## List details at http://www.exim.org/mailman/listinfo/exim-users Exim details at http://www.exim.org/ ##
>
__________________________________________________________________
John Jetmore ** jetmore@??? ** 812.461.3355 x1229
