Viktor Dukhovni:
> On Wed, Feb 25, 2015 at 12:59:59PM -0800, Quanah Gibson-Mount wrote:
>
> > We're looking to implement SRS support along the lines of
> > <https://www.mind-it.info/forward-postfix-spf-srs/>.
>
> SRS is for rewriting envelope senders *external* to your domain,
> when their email reaches a mailbox that forwards back out.
Actually, there are two mappings.
1 - Forward path: mail forwarded away from the sender (sender
rewriting)
2 - Reverse path: delivery notifications returned to the sender
(recipient rewriting).
Transformation (2) is the inverse of (1). Canonical mappings are
recursive, and combining (1) and (2) in the same canonical_maps
rule would result in a loop.
> Back to your question, any "sender" canonical rewriting you might
> have should only apply to addresses in your domains, and should
> have no effect on senders in external domains.
That is a good point. I suppose the same holds for the reverse path.
> Thus SRS should be applied only in your outbound MTA stack, when
> the envelope sender address is remote. This should have no effect
> on rewriting of outbound addresses of internal users.
The reverse SRS operation should be applied on inbound mail, to
implement the reverse path for delivery notifications.
Wietse
