Re: private relay ... could i use srs to avoid spf fail?

On Thu, 2006-11-30 at 13:22 +0000, Camart Office wrote:
> hi folks,
> 
> i would like to provide a private SMTP relay so anyone (with any email 
> address) on a particular network could use this SMTP server for outgoing 
> mail.  We can assume that this server will never be listed in any 
> domain's SPF records.
> 
> i think (please correct me if i'm wrong!) this would cause spf failure 
> .... if [email protected] is using SPF on domain.com, this would cause 
> spf failure if delivered via my relay

Yes, but that would be the fault of the recipient -- they should stop
using SPF if it's rejecting valid mail.

I _have_ set up my relay so it's able to use SRS for relayed mail -- but
it only needs to do so in the case where:
 1. The sender address has an SPF record.
 2. The recipient is known to check SPF and reject for failure.

I have a 'blacklist' of the second type of recipient, but in fact it's
empty apart from the test cases, because whenever forwarded mail has
been rejected and I've contacted the admin of the offending server
they've fixed it by no longer using SPF. So I basically never do SRS on
forwarded mail because it never matches condition #2.

> i wondered if i could use srs to get round this in some way .... treat 
> each email as if it were being forwarded from the server's default email 
> address insted.  does this sound feasable? if so, am i right in thinking 
> that the final recipient would see the 'tagged' srs address as the 
> 'from' in their email client?

It wouldn't appear in the From: address; only in the Return-Path:. But
the return-path is the most reliable way of filtering traffic from
mailing lists into the appropriate folder, so some people _do_ use it
and care about it. I would be reluctant to mangle it without good
reason.

I recommend that you don't use SRS on forwarded mail. If you find you
have problems with people rejecting mail for SPF failure, contact them
and explain that they should not be using SPF. It usually seems to work
on the people who've been taken in by the SPF 'marketing' and who didn't
realise that SPF was incompatible with mail in the real world today.

-- 
dwmw2