Re: [exim] about Sender: and envelope reverse-path in today'…

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Autor: Marc Haber
Datum:  
To: Exim User's Mailing List
Betreff: Re: [exim] about Sender: and envelope reverse-path in today's systems
On Sat, 20 Nov 2004 17:30:42 -0500 (EST), "Greg A. Woods"
<woods@???> wrote:
>[ On Saturday, November 20, 2004 at 20:18:06 (+0100), Marc Haber wrote: ]
>> Subject: Re: [exim] about Sender: and envelope reverse-path in today's systems
>>
>> It is likely amongst the user base of the majority of systems in use
>> nowadays that the owner does not have his own working mail domain.
>
>Then that person should not be running an MTA. They should be
>configuring their mail reader to send mail directly to their ISP's MTA.


Welcome to the beautiful world of UNIX on mobile clients where you
-need- some kind of local queue.

>In fact you cannot really run an MTA properly without having a proper
>domain name. What would you tell the mailer to accept as a locally
>deliverable domain when there is no private mail domain for the host?


"localhost", or "foo.local", or "foo.example".

That's fine for local delivery.

>In such a
>configuration the domain used to qualify addresses in remote-bound mail
>should be the ISP's domain, but of course the domain used for SMTP
>greetings and in message IDs should be the proper hostname of the system
>(i.e. the one that resolves to its current public IP address).


A very common configuration in Germany is that a site has a DSL line
with dynamic IP address (forced to change every 24 hours) and has a
simple NAT router to the outside. In these cases, the originating host
does not know its public IP address and cannot set the message-ID and
its HELO appropriately.

Additionally, a message might be queued when the host has IP address
a.b.c.d (having its message-ID generated appropriately), but might go
out later after the dynamic IP has changed.

>As for the "Sender:" header, well I wouldn't worry about it at all. It
>shouldn't really be used for anything much anyway, though a hub-based
>client proably shouldn't ever generate any "Sender:" header.


So the configuration change suggested by me is fine for Debian?

>Local mail on the workstation should only be used for
>system daemons and of course it should always be delivered locally by
>default.


If so, that mail is likely to be ignored by an inexperienced user.
Heck, there are people out there who have never seen an e-mail client
other than their ISP's web mail.

Greetings
Marc

-- 
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