240658Re: backupmx with Postfix
- Jul 1 10:21 AMOn Tue, 01 Jul 2008 17:33:09 +0200
mouss <mouss@...> wrote:
> Nicolas Letellier wrote:Ok, thanks for the explication! This will help me.
> > On Tue, 01 Jul 2008 11:04:53 +0200
> > mouss <mouss@...> wrote:
> >> If you have relay_recipient_maps set, then postfix will _reject_, not
> >> bounce. it is the "previous" MTA that generates the bounce. This is why
> >> you should reject on the first server that you manage and let others
> >> bounce or do whatever they want.
> > But, if Postfix rejects a mail, it sends a mail to inform that the mail has been rejected or not?
> > If rejecting a mail, Postfix send it to /dev/null and do not send any mails to sender, it's a good news!
> do not confuse "reject" and "bounce".
> here is a reject example: C is a remote client (MTA or other). S is your
> C->S: connect
> S->C: show greeting banner
> C->S: says helo
> S->C: show supported extensions (auth, tls, ... etc)
> C->S: MAIL FROM: <sender@...>
> S->C: OK
> C->S: RCPT TO: <invalid@...>
> S->C: rejected. recipient does not exist
> C->S: QUIT
> no message is exchanged here. your server does nothing after this. it
> does not send a bounce. If C is a normal MTA, it is its responsibility
> to generate a bounce, but this none of our business: we don't care.
> If on the other hand your server is misconfigured, it will accept the
> mail during the smtp transaction. then later it will find out that it
> cannot deliver the message. it will then generate a bounce and send it
> to the original sender. sometime ago, this was ok, but since a lot of
> spam uses forged addresses, such bounces go to innocent people who did
> not send anything. This is backscatter.
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