autoreply postfix

[Erik Nørgaard]

Rodrigo Mufalani wrote:

>   I want configure postfix autoreply, for undelivery mails
> 
> If one user does not exists.

The short advice: do not.

In the case you mention, user does not exist, your postfix should give a
5XX error back to the sending system. That system will then take care of
error response to the sender.

Secondly, by sending error messages whether to the one in the "MAIL
FROM" envelope field or (possibly worse) to the one in any of the
"reply-to", "from" or "return-path" mail header fields you will get
problems with spam which often forge these fields:

1) In case the recipient of the error message exist, it is likely not
the one who should have your error message.

2) In the case the recipient does not exist, this causes a double-
bounce, the error message cannot be delivered and is returned to the
postmaster mailbox - which is you.

A correctly configured server should only generate error messages to
local users when a local user's mail-delivery fails. This is already
done by postfix when a delivery attempt results in an 5XX error code.

Cheers, Erik
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