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.
> The primary issue I
> see when looking at this is we already have sender_canonical_maps set to do
> an ldap lookup for supporting alias domains:
--- Editorial ---
Firstly, I've always strongly discouraged "sender_canonical_maps".
Use canonical_maps instead. In the headers of an email message
the canonical form of an address must not depend on which header
it is found in. What is initially a sender address, easily becomes
a recipient address when someone uses reply-all.
While there may be correct use-cases for "sender_canonical_maps"
it is my best guess that almost all uses of this feature in the
field are flawed.
--- Editorial ---
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.
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.
--
Viktor.
