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> I am relatively new to postfix (great product by the way) & am
> struggling with two issues.
> 1. Specifying a different Reply To
> 2. Bouncing a message back to external incoming mail
> I have setup postfix as a relay for our systems to send messages
> though which then get passed on to a central external mail server.
> All of the mail has to be sent as the same email address in order to
> be emailed using the central external server, I am doing address
> rewrites smtp_generic_maps to converting the internal incoming
> addresses to the single email address that all mail is emailed out
> with. However I only want to write the reply to if the message has
> come from certain servers
Are you sure you understand the difference between:
- The bounce address, i.e. the RFC 5321 envelope sender address
that Internet-compliant MTAs must return undeliverable mail to.
- The Reply-To: header, i.e. RFC 5322 message header that end-user
mail agents may react to.
If the above reads like gobbledygook, then I recommend reading up
on the the documents that I have referenced above.
> Also external incoming mail is hitting the server but being rejected.
> This was going to our old exchange server, I would like to send a
> message back (assuming the headers are valid & not spam) saying the
> the email domain is no longer valid & they need to update their
> address list.
Don't. By sending email back, you would be harassing innocent people
(most email is forged) and you would get your systems blacklisted
as a backscatterer. Getting blacklisted is not good for doing email
Instead, configure your Postfix SMTP server to reply with an
appropriate 5XX reject message. If the email is spam, no-one will
be hurt. In the unlikely case that the email is real, the sending
MTA will inform the sender that email was not deliverable, with the
5XX reject message that you have configured.