[exim] Re: Is sender verification possible on a server that …

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Szerző: Chris Siebenmann
Dátum:  
Címzett: Mario Emmenlauer
CC: exim-users, Chris Siebenmann
Tárgy: [exim] Re: Is sender verification possible on a server that is used as a smarthost?
> Now I would like to configure this server as a smarthost, so it will
> forward emails from my desktop computers (without static IP or DNS).
> Also, I'd like to have unique mailnames for each desktop, like
> <hostname>.mydomain.org, to better identify where the mail originated
> from. But these domains do not really exist, they would be "fake"
> mailnames to identify the various desktop computers.

[...]
> I'm not sure if what I'm trying is possible and sensible. Am I
> completely on the wrong track here? Are there a better way to
> achieve something similar?


I think there's a problem with your plan, unless I'm missing something.

If these non-existent unique mail names for your desktop computers
appear in either the envelope sender address (the SMTP MAIL FROM) or
the From: header, this is not a good idea by itself because if you
leak these email addresses out into the outside world, the email will
either be rejected (for an envelope sender) or unreplyable (for a From:
header). Here, your existing sender verification is telling you that
you're trying to send email with addresses that don't work.

To fix this, you'd need to either make the names exist in DNS (even if
only as MX entries that direct email to mydomain.org's regular mail
server) or to change your server's Exim configuration so that it
rewrites all of these email addresses in the envelope sender and the
address headers. At that point, the only place they'd appear is in the
Received: header, and if they're only going to appear in the Received:
header my view is that you might as well not bother.

    - cks


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