Re: my solution to fight backscatter email

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my solution to fight backscatter email
\ nik600 (8 May 2008)
. \ (Wietse Venema) (8 May 2008)
. . \ nik600 (9 May 2008)
. . . \ Glenn Matthys - Webmind (9 May 2008)
. . . \ (Wietse Venema) (9 May 2008)
. . . \ Terry Carmen (9 May 2008)
. . . \ mouss (9 May 2008)

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Subject:	Re: my solution to fight backscatter email
Group:	Postfix-users
From:	mouss
Date:	9 May 2008

nik600 wrote:
> [snip]
> sorry, but i don't understand:
>
> my problem is to avoid backscatter to the users of my mailserver.
>
> I still want to forward them REAL mail delivery error.
>

the "mail delivery error" is sent to the original ENVELOPE SENDER, not
the the From header.
> with this system, i store in a database the destinations of outgoing
> email (only To: and CC:, retrieved in the header of the outgoing
> email)
>

First question: what if user BCC'd someone?
Stop using headers. Use envelope addresses.
> When i receive and email that contains the "Final-Recipient: rfc822;"
> string in the body of the incoming email, i check if the email related
> to Final-Recipient: in in my database.
>

you are doing too much assumptions. once again, use the envelope instead
of headers.

anyway, the idea is not new. see last amavisd-new "anti backscatter"
feature.

> If i found it, it means that the original mail has been sent to and
> email that my customers trust (if the email address isn't corrent, is
> not a problem).
>
> If i don't found the email Final-Recipient: rfc822; in my database, it
> means that i've never sent anything to that address, so i can delete
> the email.
>
> I what other case i send an email to someone that doesn't compare in
> the header of email? I think only when i send to mailing list, alias
> or groups, but i think that is a trascurable situation.
>
> Or not?
>
> Thanks
>