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From: Patrick Lists on 6 May 2010 09:27
Hi list,

I use a unique email address (alias) for every web(service)
registration. I would like to limit or even block spam sent to these
unique addresses. I glanced through the Postfix book but couldn't find
an answer.

Example of what should be blocked:

From: "Twitter System" <twitter(a)twitter.com> <== faked
To: <webmaster(a)mydomain.org>

Example of what should be accepted:

From: "Twitter System" <twitter(a)twitter.com> <== faked
To: <tweety(a)mydomain.org>

twitter.com and tweety(a)mydomain.org are the correct combination so
accept the email.

So I'm trying to enforce that only a combination of a certain From: ...
(the TLD) and a certain To: ... (the full email address) that was
specifically used to register with the TLD in From: ... is accepted,
otherwise REJECT.

Hope this makes sense. Anyone know if this is possible and how I can
implement this? Pointers most welcome and appreciated.

Thanks and regards,
Patrick

From: Noel Jones on 6 May 2010 10:07
On 5/6/2010 8:27 AM, Patrick Lists wrote:
> Hi list,
>
> I use a unique email address (alias) for every web(service)
> registration. I would like to limit or even block spam sent to these
> unique addresses. I glanced through the Postfix book but couldn't find
> an answer.
>
> Example of what should be blocked:
>
> From: "Twitter System" <twitter(a)twitter.com> <== faked
> To: <webmaster(a)mydomain.org>
>
> Example of what should be accepted:
>
> From: "Twitter System" <twitter(a)twitter.com> <== faked
> To: <tweety(a)mydomain.org>
>
> twitter.com and tweety(a)mydomain.org are the correct combination so
> accept the email.
>
> So I'm trying to enforce that only a combination of a certain From: ...
> (the TLD) and a certain To: ... (the full email address) that was
> specifically used to register with the TLD in From: ... is accepted,
> otherwise REJECT.
>
> Hope this makes sense. Anyone know if this is possible and how I can
> implement this? Pointers most welcome and appreciated.
>

You can use an external policy service such as postfwd to
compare envelope sender and recipient.

But it sounds as if you really need to compare the From:
header with the envelope recipient. You'll need a
content_filter or milter to do that.

-- Noel Jones

From: Patrick Lists on 6 May 2010 10:25
On 05/06/2010 04:07 PM, Noel Jones wrote:
[snip]
>
> You can use an external policy service such as postfwd to compare
> envelope sender and recipient.
>
> But it sounds as if you really need to compare the From: header with the
> envelope recipient. You'll need a content_filter or milter to do that.
>
> -- Noel Jones

Thanks Noel. I was hoping I could do it within Postfix to keep things
lean & mean. Will check out your suggestions.

Kind regards,
Patrick

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