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

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Author: Tony Finch
Date:  
To: Marc Haber
CC: exim-users
Subject: Re: [exim] about Sender: and envelope reverse-path in today's systems
On Fri, 19 Nov 2004, Marc Haber wrote:
>
> Neither RFC states that Sender: should be generated automatically.


However long-standing practice in Unix MTAs does say that it should.

> However, on today's systems is it neither guaranteed that UHacct has a
> mailbox on h.example.com, nor is it guaranteed that h.example.com is
> even reachable for SMTP from the outside at all. Hence, the automatic
> generation of Sender: and envelope sender according to the local
> account at the local host is bound to generate bad addresses on the
> majority of systems out there, most probably the ones taken care of by
> inexperienced people.


That's incompetence on the part of the machine's administrator, setting
the wrong qualify_domain. If you think this is likely amongst your user
base you should alter your friendly Exim configuration script to encourage
them to do the right thing.

> For tracing purposes, the account name and originating host can be
> obtained from the Received:-Headers, or an optional
> X-Authenticated-Sender which might be added for that purpose.
> Unfortunately, exim can add the UHacct@??? either as Sender:
> header or not at all. Maybe it would be a good idea to make the name
> of the header added with the real account information configurable,
> enabling sites to set some header like X-Authenticated-Sender to the
> real account data if they wish to.


You can add an appropriate header using Exim's existing facilities. If you
are adding a special header then it isn't appropriate to give it the
special semantics of Sender: which allow it to be omitted when it is the
same as From:.

> Wishlist request for exim upstream
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


I think these are all inappropriate for the standard Exim distribution.

Tony.
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