Blocking spam/address

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Blocking spam/address

mocherla
Hi,

I am new to postfix and thinking for a way to block the email address
which does not come from that domain. For example, if someone with a
@xxx.com email sends to a list it must come from a server in the xxx.com
domain else it should be rejected.  Is it possible to do this?


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Re: Blocking spam/address

Jorey Bump
Nandini Mocherla wrote, at 02/06/2009 12:49 PM:

> I am new to postfix and thinking for a way to block the email address
> which does not come from that domain. For example, if someone with a
> @xxx.com email sends to a list it must come from a server in the xxx.com
> domain else it should be rejected.  Is it possible to do this?

Have you thought this through? For example, nearly all legitimate
gmail.com messages come from a server in the google.com domain. That's
just the tip of a rather huge iceberg. A rule like this will reject an
enormous amount of legitimate mail. Don't take my word for it, review
your mail logs and see for yourself.


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Re: Blocking spam/address

mocherla
As there is every possibility that spammers can also send with real user's id and I am planning to have a check that would  be able to compare the From: and the Message-Id domains to check for spoofed messages coming in from an open relay. Its just an idea to eliminate every possible attack.  As i don't have much experience with postfix, just installed/configured a couple of days ago any suggestions in this regard will be highly helpful for me.  And i also have some idea of blacklists and whilists i can use with postfix but not sure where these files should live and the syntax to configure it in main.cf.  Any related documents i can find them on postfix.org?

Nandini

Jorey Bump wrote:
Nandini Mocherla wrote, at 02/06/2009 12:49 PM:

  
I am new to postfix and thinking for a way to block the email address
which does not come from that domain. For example, if someone with a
@xxx.com email sends to a list it must come from a server in the xxx.com
domain else it should be rejected.  Is it possible to do this?
    

Have you thought this through? For example, nearly all legitimate
gmail.com messages come from a server in the google.com domain. That's
just the tip of a rather huge iceberg. A rule like this will reject an
enormous amount of legitimate mail. Don't take my word for it, review
your mail logs and see for yourself.


  
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Re: Blocking spam/address

Bill Weiss-5
In reply to this post by mocherla
Nandini Mocherla([hidden email])@Fri, Feb 06, 2009 at 09:49:53AM -0800:
> Hi,
>
> I am new to postfix and thinking for a way to block the email address which
> does not come from that domain. For example, if someone with a @xxx.com
> email sends to a list it must come from a server in the xxx.com domain else
> it should be rejected.  Is it possible to do this?

You might want to look at SPF, which is a variant of what you're
suggesting.

--
Bill Weiss
 
I once bought some crack, now I'm down with the CIA
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