Re: [exim] How can exim do this?

El 02/03/2015 a las 11:56 p.m., helices escibió:
> I am tasked to design, build and maintain a new MTA. The company has
> one special requirement, for which I'm investigating the simplest solution:
>
> For each incoming message received, every outgoing "reply" must use the
> "To:" address from the incoming received message as the "From:" address
> in the outgoing reply.
>
> This is trivial when the incoming has "To: sally@???," Sally
> reads and replies, and the outgoing message has "From: sally@???"
>
> It's trickier when the incoming has "To: info@???," the MTA
> delivers to an Exchange server, which distributes that message to Sally,
> and Sally replies. What is the simplest way for that outgoing message
> to use "From: info@????"
>
> Scope is roughly one hundred (100) different domains and, possibly,
> thousands of combinations with various username@???.
>
> Ideally, the MTA will handle all of header address processing, whatever
> that process might look like. I seek the simplest solution, regardless
> how that process looks and compares to the status quo.
>
> Please, advise. Thank you.
>
> ~Mike
>
This is enforced by the MUA, not the MTA. You should confiogure the mail
client program to use diferent identities and there the "reply" button
choose the right "from". If you think that some user will forge a fake
"from", you should do a propper authentication and there see what
aliases this address belongs and permit or deny the relay.

But if you still want to do it, with exim you can do this:
record in a database every "to", "cc" and "message-id" header from
incoming mails (on MX servers) and enforce an acl to check the
"in-reply-to" and "references" headers, and if they match with, rewrite
the from (on smtp servers). I think this is done in ACLs... but read
carefully the RFC on this headers and the exim manual to achieve, it can
be done, but's not easy.

Saludos, Juan