From: "J.R.Ewing" on
Hello people,

Iam trying to solv a problem with relaying. I want to setup a
distribution list for one domain, where will postfix only relay email
for mydomain.com to selected users email addresses. No local mailboxes,
only realaying list. Its quite simple, but.. but if I try to relay email
comming from SPF active (has active SPF in DNS) server and it is relayed
to SPF protected server (checking validity of sending server if SPF is
present in DNS for the sending domain), it is rejected, because of
course my server is not valid sending server for that domain.
Is there any solution?
I have idea to move senders address to "reply to" field and write new
sender. Is it possible with postfix?

Thanks

J.R.

From: Ralf Hildebrandt on
* J.R.Ewing <jr.ewing(a)radobyl.eu>:
> Hello people,
>
> Iam trying to solv a problem with relaying. I want to setup a
> distribution list for one domain, where will postfix only relay email
> for mydomain.com to selected users email addresses. No local
> mailboxes, only realaying list. Its quite simple, but.. but if I try
> to relay email comming from SPF active (has active SPF in DNS) server
> and it is relayed to SPF protected server (checking validity of
> sending server if SPF is present in DNS for the sending domain), it
> is rejected, because of course my server is not valid sending server
> for that domain.
> Is there any solution?

Yes, SRS
--
Ralf Hildebrandt
Geschäftsbereich IT | Abteilung Netzwerk
Charité - Universitätsmedizin Berlin
Campus Benjamin Franklin
Hindenburgdamm 30 | D-12203 Berlin
Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962
ralf.hildebrandt(a)charite.de | http://www.charite.de


From: Ralf Hildebrandt on
* Ralf Hildebrandt <Ralf.Hildebrandt(a)charite.de>:

> Yes, SRS

http://en.wikipedia.org/wiki/Sender_Rewriting_Scheme

--
Ralf Hildebrandt
Geschäftsbereich IT | Abteilung Netzwerk
Charité - Universitätsmedizin Berlin
Campus Benjamin Franklin
Hindenburgdamm 30 | D-12203 Berlin
Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962
ralf.hildebrandt(a)charite.de | http://www.charite.de


From: Simon Waters on
On Thursday 01 April 2010 12:38:29 J.R.Ewing wrote:
>
> Is there any solution?
> I have idea to move senders address to "reply to" field and write new
> sender. Is it possible with postfix?

As Ralph says SRS will do this.

However I looked at this recently for a project, where I thought I'd need SRS,
and after reviewing the various issues and SPF adoption figures, concluded
I'd ignore SPF.

In particular very few people reject outright on SPF failure (not least this
isn't a good strategy compared to other filtering methods if all you want to
do is reduce spam). Various systems handle SPF failed email in a more
suspicious manner, but that isn't a practical problem in my experience.

SRS might work better for your purpose, but SPF is broken by design and you
should flag that to the people using it.

We forward a lot of email, we don't do envelope rewriting, and have had a
handful of complaints over the years, most from the same person who didn't
seem to understand "we have no plans to change at this time".

From: "J.R.Ewing" on
Simon Waters napsal(a):
> On Thursday 01 April 2010 12:38:29 J.R.Ewing wrote:
>> Is there any solution?
>> I have idea to move senders address to "reply to" field and write new
>> sender. Is it possible with postfix?
>
> As Ralph says SRS will do this.
>
> However I looked at this recently for a project, where I thought I'd need SRS,
> and after reviewing the various issues and SPF adoption figures, concluded
> I'd ignore SPF.
>
> In particular very few people reject outright on SPF failure (not least this
> isn't a good strategy compared to other filtering methods if all you want to
> do is reduce spam). Various systems handle SPF failed email in a more
> suspicious manner, but that isn't a practical problem in my experience.
>
> SRS might work better for your purpose, but SPF is broken by design and you
> should flag that to the people using it.
>
> We forward a lot of email, we don't do envelope rewriting, and have had a
> handful of complaints over the years, most from the same person who didn't
> seem to understand "we have no plans to change at this time".


Thanks Simon and Ralf for replies,

I was observing SRS and it lookslike there is not a simple way to
implement it with postfix.
Because Iam just starting to relaying at my server, I will let some time
to see, if there are some major problems with it or if it works
unnoticed for users. Sad is, that the major freemail provider
(seznam.cz) here in Czech Republic sadly implement and enforce SPF, the
question is, how many domains that our users would be recieving from are
SPF "protected" (I know only one, at domain of our company :-/).

Thanks again

J.R

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