Re: [exim] pretend a different domain

On Tue, Aug 09, 2016 at 04:14:49PM +0200, hw wrote:
> with several domains declared as local domains, users can
> send and receive messages with sender addresses the domain
> part of which is any of the local domains.

There are no built-in restrictions for the sender's domain part:
by default senders can eject e-mails from arbitrary envelope
addresses and with arbitrary headers.

> Unfortunately,
> when looking at the headers, the recipient can always see
> from which domain the message was actually sent because of
> headers like Received: and Sender:, and the envelope information.

May be you mean these headers exibit information about mail host.
Host may be declared local for several domains, that's true.

> Is there a way to make it so that the recipient of a message
> sent from <user@???> cannot figure out that the message
> was actually sent from <user@???> when the host exim
> runs on has a primary hostname like mx.domain-a.net?

You may delete some headers in Exim routers or transports.
Look for headers_remove options in documentation (ch. 47 p. 17).

> Do I need to set up another email server for this?

Yes. You may also run several Exim instances on the same host,
however, this is slightly tricky in configuration.
--
Eugene Berdnikov