Mailing List Archive: exim: users

Exim/Postfix once again

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exim-users at pollok

Oct 2, 2007, 4:18 AM

Post #1 of 7 (2864 views)
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Exim/Postfix once again

Good day folks,

I am unsure whether this question belongs here or to Fetchmail.
I am quite sure though, that it might have already been discussed.
I wasnt able to find anything helpful in the archives so please
bear with me if this is a FAQ.

A user is using a multidrop box for his domain name. He picks this
up using fetchmail and distributes it to several users. He is
using the Envelope-To header to detect the recipients of the
single e-mail and distributes it among local users at his server.

In case an e-mail has multiple recipients, Exim does not add the
"for" address in the Received header so he needs to rely on those
Envelope-To header, which might be better anyway. He is now complaining
that user's addresses who received the e-mail as a Bcc are leaked
to other recipients because of the Envelope-To header.

The question if it is possible to strip the envelope-to header after
analysing it might be a question for the Fetchmail folks (I would be
happy about a hint anyway). Fetchmail manual however suggests that
the MTA stores one e-mail per recipient in the box although it is
actually the same box and adding proper Envelope-To or X-Envelope-To
headers.

Can someone help me with a hint/best practice scenario how to achive
this? I have searched the Exim-docs over and over again but was
not able to find any information (not saying that it is not there ;-)).

Thank you
Sascha

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hs at schlittermann

Oct 2, 2007, 5:00 AM

Post #2 of 7 (2745 views)
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Re: Exim/Postfix once again [In reply to]

Hi Sascha,

Sascha E. Pollok <exim-users [at] pollok> (Di 02 Okt 2007 13:18:53 CEST):
> Good day folks,
>
> A user is using a multidrop box for his domain name. He picks this
> up using fetchmail and distributes it to several users. He is
> using the Envelope-To header to detect the recipients of the
> single e-mail and distributes it among local users at his server.
>
> In case an e-mail has multiple recipients, Exim does not add the
> "for" address in the Received header so he needs to rely on those
> Envelope-To header, which might be better anyway. He is now complaining
> that user's addresses who received the e-mail as a Bcc are leaked
> to other recipients because of the Envelope-To header.

I think, exim can't know if some of the recpient (it laters stuffs into
Envelope-To) were BCCs.

If fetchmail likes to rely on these headers they should stay untouched.

> analysing it might be a question for the Fetchmail folks (I would be
> happy about a hint anyway). Fetchmail manual however suggests that
> the MTA stores one e-mail per recipient in the box although it is
> actually the same box and adding proper Envelope-To or X-Envelope-To
> headers.

I do not know if you can ask exim to "explode" the message into single
ones (except some "loop" delivery to itself).

But you can refuse accepting more than one recipients per message in the
recpient acl. (Not sure, but it should work responding with "defer" to
all RCPTs, except the first one, of course).

(PS: Subject should be Exim/Fechmail?)

Greetings from Dresden, "up the river Labe" :)
--
Heiko

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exim-users at pollok

Oct 2, 2007, 5:33 AM

Post #3 of 7 (2744 views)
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Re: Exim/Postfix once again [In reply to]

Heiko,

> > analysing it might be a question for the Fetchmail folks (I would be
> > happy about a hint anyway). Fetchmail manual however suggests that
> > the MTA stores one e-mail per recipient in the box although it is
> > actually the same box and adding proper Envelope-To or X-Envelope-To
> > headers.
>
> I do not know if you can ask exim to "explode" the message into single
> ones (except some "loop" delivery to itself).
>
> But you can refuse accepting more than one recipients per message in the
> recpient acl. (Not sure, but it should work responding with "defer" to
> all RCPTs, except the first one, of course).

Hm ... this would be a possible way, yes. Maybe someone else knows if
there is a way to enable those kind of "duplicate local deliveries"
in Exim?

> (PS: Subject should be Exim/Fechmail?)

Indeed .. oh lord I need a nap.

> Greetings from Dresden, "up the river Labe" :)

Your box sends greetings to Dresden :-)

Cheers
Sascha

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nigel.metheringham at dev

Oct 2, 2007, 5:35 AM

Post #4 of 7 (2729 views)
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Re: Exim/Postfix once again [In reply to]

On 2 Oct 2007, at 13:00, Heiko Schlittermann wrote:

> Sascha E. Pollok <exim-users [at] pollok> (Di 02 Okt 2007 13:18:53
> CEST):
>> Fetchmail manual however suggests that
>> the MTA stores one e-mail per recipient in the box although it is
>> actually the same box and adding proper Envelope-To or X-Envelope-To
>> headers.

> I do not know if you can ask exim to "explode" the message into single
> ones (except some "loop" delivery to itself).

Set batch_max=1 on the appendfile transport you are using.

See
http://www.exim.org/exim-html-current/doc/html/spec_html/ch25.html

Nigel.
--
[ Nigel Metheringham Nigel.Metheringham [at] InTechnology ]
[. - Comments in this message are my own and not ITO opinion/policy - ]

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hs at schlittermann

Oct 2, 2007, 6:07 AM

Post #5 of 7 (2742 views)
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Re: Exim/Postfix once again [In reply to]

Nigel Metheringham schrieb:
>
> Set batch_max=1 on the appendfile transport you are using.

Thank you (even I didn't ask for it :))

--
Heiko

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exim-users at pollok

Oct 2, 2007, 8:00 AM

Post #6 of 7 (2726 views)
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Re: Exim/Postfix once again [In reply to]

Nigel,

thanks for your e-mail. It gave me a big "ahaaa" but unfortunately
I am still a little bit confused:

> >> Fetchmail manual however suggests that
> >> the MTA stores one e-mail per recipient in the box although it is
> >> actually the same box and adding proper Envelope-To or X-Envelope-To
> >> headers.
>
> > I do not know if you can ask exim to "explode" the message into single
> > ones (except some "loop" delivery to itself).
>
> Set batch_max=1 on the appendfile transport you are using.
>
> See
> http://www.exim.org/exim-html-current/doc/html/spec_html/ch25.html

According to this link, the default for batch_max is 1 which should result
in no batching at all. However we have not used batch_max so far in
our local transport:

local_delivery_mysql:
driver = appendfile
delivery_date_add
envelope_to_add
return_path_add
#group = mail
#user = mail
mode = 0660
directory_mode = 770
mode_fail_narrower = false
maildir_format
directory = ${lookup mysql{MYSQL_LOCALUSER_HOME}{$value}{'fail'}}

Thus, we assume that the default of batch_max is active (1) but we still
see e-mails with multiple recipients pointing to the same postbox
only once.

Happy for any advice
Sascha

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hs at schlittermann

Oct 2, 2007, 3:37 PM

Post #7 of 7 (2722 views)
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Re: Exim/Postfix once again [In reply to]

Sascha Pollok <exim-users [at] pollok> (Di 02 Okt 2007 17:00:20 CEST):
> Nigel,
>
> thanks for your e-mail. It gave me a big "ahaaa" but unfortunately
> I am still a little bit confused:
>
> > >> Fetchmail manual however suggests that
> > >> the MTA stores one e-mail per recipient in the box although it is
> > >> actually the same box and adding proper Envelope-To or X-Envelope-To
> > >> headers.
> >
> > > I do not know if you can ask exim to "explode" the message into single
> > > ones (except some "loop" delivery to itself).
> >
> > Set batch_max=1 on the appendfile transport you are using.
> >
> > See
> > http://www.exim.org/exim-html-current/doc/html/spec_html/ch25.html
>
> According to this link, the default for batch_max is 1 which should result
> in no batching at all. However we have not used batch_max so far in
> our local transport:
>
> local_delivery_mysql:
> driver = appendfile
> delivery_date_add
> envelope_to_add
> return_path_add
> #group = mail
> #user = mail
> mode = 0660
> directory_mode = 770
> mode_fail_narrower = false
> maildir_format
> directory = ${lookup mysql{MYSQL_LOCALUSER_HOME}{$value}{'fail'}}

And furthermore: MYSQL_LOCALUSER_HOME probably contains a reference to
$local_part, which in turn prevents batching anyway.

> Thus, we assume that the default of batch_max is active (1) but we still
> see e-mails with multiple recipients pointing to the same postbox
> only once.

It's strange - are you sure about the used transport (double check the
log).

I tested it here - and got confused - until I "discovered" that
local_delivery isn't used in favour of a pipe transport (due to
procmail). Using batch_max in the *used* transport has the expected
influence on (to?) the Envelope-To-header. (4.63)

--
Heiko

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