240647Re: backupmx with Postfix
- Jul 1, 2008Nicolas Letellier wrote:
> On Tue, 01 Jul 2008 11:04:53 +0200do not confuse "reject" and "bounce".
> 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!
here is a reject example: C is a remote client (MTA or other). S is your
S->C: show greeting banner
C->S: says helo
S->C: show supported extensions (auth, tls, ... etc)
C->S: MAIL FROM: <sender@...>
C->S: RCPT TO: <invalid@...>
S->C: rejected. recipient does not exist
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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