Re: [exim] how can exim 4.54 check for valid 'non-local' use…

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Author: Marco Wessel
Date:  
To: exim-users
Subject: Re: [exim] how can exim 4.54 check for valid 'non-local' users when acting as a MX gateway for remote uucp sites?

On Mar 17, 2007, at 5:03 PM, Urs Rau wrote:

> Thanks for this. I have had a look at
>
> http://www.exim.org/exim-html-4.66/doc/html/spec_html/
> ch40.html#SECTcallver


> and it seems to me that the callouts all assume they can make a smtp
> or lmtp connection to the recipients (or senders) site. Which of
> course in my case is not possible, as all of the uucp end nodes are
> not permanently online and there is no running smtp process at the end
> point.


I see.

> I guess this 'recipient' callout verification would logically be the
> correct place to 'plug-in' another verification that could read a
> berkeley db file or query a mysql table or something like that.


That would then be the only option: you would need a list of all
existing e-mail addresses. This list can be in any file searchable by
exim (flat file, db file, mysql, even ldap would work). Then you
would add a router to your config that is used only for verification
(using the verify_only option) and simply accepts all addresses in
the list. Then, set your current uucp router to not be used for
verification (no_verify option), and I think you should be set. You
can also do this in an RCPT ACL by checking the list and denying the
message if the recipient isn't in it. Which of these options is best
depends on your setup.

> I don't suppose you are aware of a method that exim already knows to
> use, that I could call out to at this point?


Well, if your receiving machine(s) aren't permanently online, having
a list locally at exim is the only option really.