Stan Hoeppner wrote:
Jim Lang put forth on 11/16/2009 2:00 PM:
Wietse Venema wrote:
Jim Lang:
OK here is the scenario.
Spammer sends mail to: u...@myclientsdomain.com from forged address
vic...@randomdomain.com
If u...@myclientsdomain.com is delivered locally, not a problem, if
the address is invalid, postix rejects the mail during the smtp
connection.
But if u...@myclientsdomain.com is an alias to
mycli...@otherserver.com, postfix accepts the mail as deliverable and
forwards it to hotmail.com.
But if mycli...@otherserver.com can for whatever reason not be
delivered, otherserver.com does what it is supposed to do and rejects
the mail during the smtp connection, which causes postfix to send out
a non-delivery report to vic...@randomdomain.com -- backscatter.
Is there a way to stop this?
Yes. Don't forward SPAM.
Wietse
And how do I do that in this scenario?
You don't do it "in this scenario". You set up comprehensive spam
rejection techniques, one of which is identifying forged email, and
reject spam when it hits your MX.
Dozens of books have been written, and dozens of email lists are
maintained, specifically for fighting spam. The answer to your scenario
isn't a simple one paragraph response on postfix-users.
What are you doing up to this point to reject spam at your border MX(s)?
I'm doing many, many things. And I certainly don't have the time to
enumerate them all simply to prove my bona fides.
No one responding to this post seems to have actually bothered to read it.
Generic, rtfm responses such as "don't forward spam" may be emotionally
satisfying but they are really a waste of everyone's time.
As was asking for advice at this list.
I'll figure it out for myself.
