[ 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.
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?
You definitely should not be trying to use a full-blown MTA like Exim in
it's full-blown full-featured configuration just for sending only.
I suspect, though I'm not familiar enough with Exim's detailed
configuration, that there's a really simple way to lop most of the mail
routing smarts out of Exim and to convince it to act only as a simple
forwarder and have it forward everything (except maybe locally
deliverable mail addressed to unqualified addresses) to the ISP's
mailer. Often this is called a "hub" configuration. 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).
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.
The SMTP envelope sender address in forwarded transactions is what's
really most important and it should of course be the same as the "From:"
address (i.e. <isp-user-id@???>) and it MUST NOT EVER use the
client hostname since that would not result in a deliverable address!
It should be much easier though to simply set up Exim on a personal
workstation as a local-only mailer that never routes remote mail
remotely and to have the workstation users always send their remote mail
using an MUA that can submit mail to the ISP via SMTP (or SUBMIT).
E.g. even command-line mailers such as pine can and should be configured
by default in such a scenario to use the ISP's SMTP (or SUBMIT) port for
mail submission. Local mail on the workstation should only be used for
system daemons and of course it should always be delivered locally by
default.
--
Greg A. Woods
+1 416 218-0098 VE3TCP RoboHack <woods@???>
Planix, Inc. <woods@???> Secrets of the Weird <woods@???>
