Hi Mike,
> 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@????"
First of all: Are you talking about the To:-Header or about the RCPT-TO
evenlope Line. The first one doesn't need to be related to the real
recipient at all!
-> RCPT TO:<sally@???> ---> [ mbox of sally ] ---> MTA
-> RCPT TO:<info@???> ---> [ mbox of sally ] ---> MTA
The MTA won't care about the recipient address, even if you put there
an additional Envelope-To header.
If you relay the reply from the MTA there is no information about
the original message, the user is replying to. (What, if the user
replies to two messages at once?)
You can try to save the inbound Message-ID and the RCPT-TO information.
If you have well behaving clients/MTAs, they will reference that
Message-ID in their response. This information you can use for address
rewriting on the outgoing message.
Some other approach would be to encode the recipient of the incoming
message in its From:-Header, since most MTAs will use this header for
their reply (except there is some Reply-To). This information then needs
to be extracted from the reply and can be used for header rewriting. But
this will probably break some automatic address books. (Beware:
From-Header may contain >1 addresses!)
From: info@???
-> From: sally@???+info@???
The reply will carry this information in the Envelope-Recipient… There
it could be extracted…
[I'd use the message-id approach, seems to be cleaner, but probably
needs some maintanance.]
Best regards from Dresden/Germany
Viele Grüße aus Dresden
Heiko Schlittermann
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