Re: [Exim] [Spoofed Mail addresses spamming mails]

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Autor: Giuliano Gavazzi
Datum: 2004-02-03 09:59 -000
To: linuxclassic, exim-users
Betreff: Re: [Exim] [Spoofed Mail addresses spamming mails]
At 2:41 pm +0530 2004/02/03, Vibhav wrote:
>Dear List
>
>I have a problem in my exim server, spammers are telnetting to my server
>using port 25 and making local delivery to unexisting email accounts ,
>which in turn my exim server returns a error message to the sender and
>most of those mails are bounced and comes back to my postmaster account.
>
>I have smtp auth and open relays closed, as this is a local delivery
>mail issue, how to curb this?
>


well, this is one of those questions that contain the answer in
themselves... read your own message again.

Do not accept delivery for unknown local parts!
This is, btw, in the standard accept/endpass block:

   accept  domains       = +local_domains
           endpass
           message       = unknown user
           verify        = recipient


and do not allow catchall aliases.


Also, it cannot be that error message returns back to the postmaster,
an error message has <> envelope sender, so at most it is an
undeliverable error message (for instance for undeliverable domain)
that goes back to postmaster.

So, I also suggest that you require verify = sender, BEFORE accepting
for local domains.

As it seems you are configured now you are just a source of collateral spam.

Giuliano
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