From: Marian Boboc (bobocilvillage.it)
Date: Mon May 28 2007 - 05:27:01 CDT

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Hi,
What I want in fact is not to reject at all.
To be more explicit I'll give an example:

Spammer sends mail to user1example.com, user2example.com,
user3example.com.
On my system only user2example.com exists; for the other two destinations
postfix will reject the message with 550 (the sender receives the
notification of the rejected message) and of course the spammer will know
that user2example.com is a valid e-mail, while the others are not.
This method is widely used by spammers to get valid e-mails for the various
domains.

Now, what I want is not to reply al all in these cases, just to drop the
mail somehow.

-----Original Message-----
From: owner-postfix-userspostfix.org
[mailto:owner-postfix-userspostfix.org] On Behalf Of mouss
Sent: lunedì 28 maggio 2007 12.02
Cc: postfix-userspostfix.org
Subject: Re: 550

Marian Boboc wrote:
> Hi list,
> I'd like to have postfix not reply to the sender while receiving mail
> destined to an unknown local user. I know it's not ethical but the
> spam's a killer.
>
> Any idea on how this can be done?
>
>
>
>

you mean not to bounce (send back an error message)? Bouncing is
unacceptable. you should either reject the mail during the smtp transaction
or keep it on your system (deliver, discard, ...).

by default, postfix rejects mail sent to unknown users. if that is not the
case on your system, then you broke recipient validation. if you have
wildcard aliases, replace them with "explicit" (not regex/pcre) aliases. if
you have virtual aliases like
/(.*)example.com/ $1example.org
then that's it. you can either use a script to generate per-user aliases, or
use sql or ldap to only return a result if the target address is valid.

for more help, you must follow the welcome message instructions (repeated
here multiple times). see
    http://www.postfix.org/DEBUG_README.html#mail

in particular, you must send output of 'postconf -n' (this is not main.cf).

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