Re: Question abour SRS in sendmail

On Tue, 19 Jul 2005 [email protected] wrote:

> On Tue, Jul 19, 2005 at 10:08:50AM -0300, Fernando Trindade Xavier - Fumsoft wrote:
> >     I've read about the Mail SRS and the problem of the forwarded
> > e-mail. I thing I got this problem. Some accounts in my server needs to
> > be forwarded to anothers accounts, and that servers wich have spf
> > records are rejecting these forward e-mail's. I guess that the solution
> > is rewriting the sender address, but how can I do that in sendmail ???
> 
> Aside: first you might want to consider whether you ought to be breaking
> *your* mail system, in order to get mail through to someone else's broken
> mail system.

You are correct the the receiving mail system is broken.  However, the
problem is not SPF, but an incorrect implementation of SPF.
A pre-requisite for strict checking of SPF is that a mail receiver
identify all forwarders.  The receiver in question obviously did not 
do that, and hence should have been using relaxed checking 
(add a Received-SPF header, but do not reject mail, and let a
content filter sort it out).

If SPF has a problem, it is that just as buffer overflow bugs are too
easy to commit in the C language, so it is too easy for SPF noobies
to miss the requirements for strict checking.  They ignore the
advice to start in relaxed mode until they know what they are doing, and jump
right to strict without meeting the requirements.

You should not have to use SRS just because some receiver is broken.
I would first call up the receiving system (NOT the system that published
SPF records) and explain that they or their customer requested the forward
from your system, and if they want it to work, they need to accept
the forward from your system.  

SRS was intended as a tool to make managing forwards easier for 
a receiver.

However, SRS also works as a bandaid for broken receivers in most cases.

-- 
	      Stuart D. Gathman <[email protected]>
    Business Management Systems Inc.  Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flamis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.