--On 20 November 2008 17:50:03 -0500 Rick Duval <rick@???> wrote:
> But my server gets thousands of messages to non-existent local_parts
> and some spammers send them all from some poor guys address (I know
> I've been on the victim side of that where someone is spamming and
> using my address in the from header).
>
> I'm not only concerned that I'll be flooding that server with rejected
> emails but also that my server could end up blacklisted because of the
> potential flood of replies generated.
Note that rejecting a message at SMTP time (using "deny" in an ACL, for
example) is different from accepting it and then generating a bounce
message. If you reject a message, then it is the responsibility of the
sending server to generate any bounce message. Spammers don't bother.
Your "deny" isn't generating the bounce. The sending MTA is generating the
bounce. If it's a false positive, then that's a good thing because the
original sender needs to know.
> Rick
>
> On Thu, Nov 20, 2008 at 5:44 PM, Kjetil Torgrim Homme
> <kjetilho@???> wrote:
>> On Thu, 2008-11-20 at 17:24 -0500, Rick Duval wrote:
>>> I now have a lookup that accepts emails only for addresses that are in
>>> the database.
>>>
>>> accept condition = ${lookup mysql{SELECT count(*) from addresses \
>>> WHERE active AND domain='${quote_mysql:$domain}'
>>> \ AND local_part='${quote_mysql:$local_part}'}}
>>>
>>> deny
>>>
>>> It works great but I don't want to contribute to backscatter by
>>> sending denial messages back to the sender everytime an address is
>>> rejected. Right now it sends out and email like:
>>>
>>> SMTP error from remote mail server after RCPT TO:<bob@???>:
>>> host duvals.ca [74.51.38.171]: 550 5.1.1 <bob@???>:
>>> Recipient address rejected: User unknown in virtual alias table
>>>
>>> Can I turn that off and just not have it reply at all?
>>
>> well, you can blackhole the message, but your current method is the
>> recommended way of setting it up. if someone mistypes an address, say
>> "bpb@???", you will typically want him to know about it so that he
>> can resend it using the correct address.
>>
>> you won't be contributing to backscatter unless someone forwards e-mail
>> to you -- and typoes in forwarding targets should definitely be
>> reported.
>>
>> it's a bit different if your denial is due to a SpamAssassin score or
>> something like that -- then the forwarding system may have more lax spam
>> filtering than your system, but it's the forwarding's system which will
>> be spreading backscatter. even here, it's not really your fault.
>>
>> --
>> regards, | Redpill _
>> Kjetil T. Homme | Linpro (_)
>>
>>
>> --
>> This message has been scanned for
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>>
--
Ian Eiloart
IT Services, University of Sussex
x3148
