[ExchangeList] Re: Drop emails

  • From: <ChongJa@xxxxxxxxxxxxxxxx>
  • To: <exchangelist@xxxxxxxxxxxxx>, <exchangelist@xxxxxxxxxxxxx>
  • Date: Fri, 12 May 2006 18:56:25 -0400

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Your thought process is assuming that all SPAM\AV attacks are brute force DOS 
attacks. Some are some aren't, some attackers still try to guess valid invalid 
recipients and thus the answer to the question. 

________________________________

From: exchangelist-bounce@xxxxxxxxxxxxx on behalf of John T (Lists)
Sent: Fri 5/12/2006 6:26 PM
To: exchangelist@xxxxxxxxxxxxx
Subject: [ExchangeList] Re: Drop emails



Your thought process is old and no long valid. There have been quite a number 
of viruses and spam campaigns in the last year that do not care about valid or 
invalid recipient. They try to force as much as possible. In this sense, part 
of the intent is to overwhelm and create a sort of DOS attack on the receive 
system. The sheer volume of messages in those kinds of campaigns far outweigh 
the obscurity of accepting all then dropping invalid. 

 

John T

eServices For You

 

"Seek, and ye shall find!"

 

-----Original Message-----
From: exchangelist-bounce@xxxxxxxxxxxxx 
[mailto:exchangelist-bounce@xxxxxxxxxxxxx] On Behalf Of ChongJa@xxxxxxxxxxxxxxxx
Sent: Friday, May 12, 2006 12:57 PM
To: exchangelist@xxxxxxxxxxxxx
Subject: [ExchangeList] Re: Drop emails

 

Some AV filters will accept all emails for invalid accounts, that way someone 
attempting to perform a DHA attack cannot determine valid accounts. You can 
enable recipient filtering but this in itself is susceptible to DHA attacks 
because the SMTP connection will drop if you specify an invalid account telling 
you user does not exist or something to that effect.

 

________________________________

From: exchangelist-bounce@xxxxxxxxxxxxx 
[mailto:exchangelist-bounce@xxxxxxxxxxxxx] On Behalf Of John T (Lists)
Sent: Friday, May 12, 2006 3:47 PM
To: exchangelist@xxxxxxxxxxxxx
Subject: [ExchangeList] Re: Drop emails

But the question that begs to be asked is why do you want to accept e-mail for 
invalid accounts in the first place?

 

John T

eServices For You

 

"Seek, and ye shall find!"

 

-----Original Message-----
From: exchangelist-bounce@xxxxxxxxxxxxx 
[mailto:exchangelist-bounce@xxxxxxxxxxxxx] On Behalf Of Bruce J. Rose
Sent: Friday, May 12, 2006 10:33 AM
To: exchangelist@xxxxxxxxxxxxx
Subject: [ExchangeList] Drop emails

 

Is it possible to have the exchange server accept delivery for invalid accounts 
and dump them?

 

Thanks Bruce

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