Re: [Declude.JunkMail] Gateways and CMDSPACE conundrum

2004-04-08 Thread Matt




Sandy et al.,

Regarding how peering is handled, that sucks! It was a bit of a kludge
anyway, more than most at least.

I just got mail bombed on both servers by three different ISP relays.
The recipient address was invalid (sent to and from itself), and if I
had MS SMTP/ORF configured on both machines to blacklist invalid
addresses (instead of just the domain on the backup as is done
currently), this would have stopped that attack cold without me lifting
a finger. Instead I was stuck scanning as many as 15 incoming messages
per second, or at least trying to do so, but not succeeding. Worse
yet, the destination server was bouncing NDR's back through our server
and each of those were being virus scanned despite the original being
in plain text.

I've also noticed that there are a couple hundred E-mails a day in the
backup's BadMail directory for locally hosted domains with non-existant
accounts. I'm only hosting about 300 accounts in total, and this is
all to just those addresses and not the gatewayed domains. Address
validation would stop these needless bounces to forged addresses from
my servers and help to clean up the Internet.

I have a feeling that the need for CMDSPACE detection falls far short
of the need for address validation for gatewayed domains. ORF seems to
be a great tool for this because I can do things like configure a local
RBL for instance to block virus sending machines on the gateway by
maintaining a single zone, along with sender and recipient
blacklisting. ORF of course is a very limited spam blocking tool at
the moment and not appropriate for such needs.

I'm still thinking about approaching IMail for a solution to recipient
blacklisting on gatewayed domains using an 'everything but'
methodology. How unrealistic do you think that would be??? It might
just be easier to ask VAMSoft for CMDSPACE header logging and dealing
with the two separate pieces of technology.

Matt


Sanford Whiteman wrote:

  
With  a recent IMail release, you can now set up peering to use RCPT
TO  to  test  incoming  messages for valid senders.

  
  
Right,  but  the resulting envelope behavior is not different from the
old VRFY scenario, AFAIK.

  
  
As  long  as  IMail  does envelope rejection for peered domains that
fail  validation,  this setup should work.

  
  
There's  never  been  real-time validation and rejection with peering.
With just IMail servers, the idea is that a message can enter a "farm"
of peers and will only be bounced (not rejected) after the message has
been  spooled and delivery attempted at every peer. Once you add an MS
SMTP server into the mix, you only have one-way peering.

Maybe  I'm  not  clear  on  what you're suggesting, but I don't see it
shedding any light on your issue.

--Sandy



Sanford Whiteman, Chief Technologist
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Cypress Integrated Systems, Inc.
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Re: [Declude.JunkMail] Gateways and CMDSPACE conundrum

2004-04-06 Thread Matt




Sandy,

Am I correct in assuming that you attempted something similar to the
following script on the VAMSoft site?

 Envelope header information
 http://www.vamsoft.com/orf/tools.asp#smtpenvl

This is how they add headers to the messages containing the MAIL FROM
and RCPT To data. I get the feeling from reading the code that they
are using some sort of pre-normalized data that MS SMTP spits out,
though I'm not at all sure about that. If this data isn't normalized,
then this would seem to do the trick with a little bit of modification.

Thanks,

Matt



Sanford Whiteman wrote:

  
I'm eagerly awaiting the results of your research :)

  
  
Well,  I  wish  I  had  better news, but the problem (they'd call it a
feature,  and for once I think I'd agree) is that MS SMTP "normalizes"
the  envelope  fields  as  part  of of normal message flow. Thus, even
though  the  IIS and ORF logs will show extra spaces, they're the only
place where the actual protocol commands are preserved. ORF doesn't do
anything  special  to  change this data; it just automatically changes
after  the  message  is  submitted,  and subsequent message inspection
during  MS SMTP transport will not show any of the original formatting
errors.

The  only  way you could retain the protocol-level data is by plugging
in  another  protocol  event sink alongside ORF, but running more than
one  custom  PES  on  the same system is pretty un-heard-of (I believe
it's  possible  using  different priorities, but I've never seen it in
practice).  So  you  are  pretty much stuck with (a) giving up, or (b)
trying  the log inspection option. I really wouldn't trust the latter,
since  you  might  actually have to throttle _down_ processing to make
sure   that   the  logs  can  be  parsed  in  time  to  intercept  the
message...not good.

Sorry I don't have a fix.

--Sandy



Sanford Whiteman, Chief Technologist
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Cypress Integrated Systems, Inc.
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Re: [Declude.JunkMail] Gateways and CMDSPACE conundrum

2004-04-06 Thread Matt




Sandy,

Well, I haven't yet given up. For one, I could ask that VAMSoft if
they could allow for header tagging of this type. There is another
kludge though that I am thinking might be of use here...

With a recent IMail release, you can now set up peering to use RCPT TO
to test incoming messages for valid senders. You could set up each
gateway domain to peer off of the ORF enabled instance of MS SMTP for
validation with RCPT TO, and then it would handle delivery according to
your host file settings (MS SMTP has better queue settings anyway). As
long as IMail does envelope rejection for peered domains that fail
validation, this setup should work. I do understand of course that
this would be somewhat limiting in terms of capacity due to the delay
while checking the RCPT TO, however if installed on the same box or
network, this should be very quick.

I'm hoping that down the line IMail will have the ability to do
envelope rejection for gatewayed domains, and if that comes, you could
just strip out the MS SMTP/ORF part without needing to totally retool
your environment.

What do you think?

Matt



Sanford Whiteman wrote:

  
Am I correct in assuming that you attempted something similar to the
following script on the VAMSoft site?

  
  
In  the  same  vein, yes (though actually part of an existing compiled
sink that we wrote).

  
  
This  is  how  they  add headers to the messages containing the MAIL
FROM  and RCPT To data. I get the feeling from reading the code that
they  are  using some sort of pre-normalized data that MS SMTP spits
out,  though  I'm  not  at  all  sure about that.

  
  
Yes, MS SMTP's envelopefields collection is all normalized, and that's
all   that's   available   after   submission.   That's   what  I  was
double-checking,

--Sandy



Sanford Whiteman, Chief Technologist
Broadleaf Systems, a division of
Cypress Integrated Systems, Inc.
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Re: [Declude.JunkMail] Gateways and CMDSPACE conundrum

2004-04-05 Thread Sanford Whiteman
Matt,

Let  me  do  some  research  tonight;  it's  possible that I will have
something  tomorrow  that  will  let  you forward through the incoming
envelope  stuff  in  an  x-  header. (I shudder to think about the log
parsing alternative.)

--Sandy



Sanford Whiteman, Chief Technologist
Broadleaf Systems, a division of
Cypress Integrated Systems, Inc.
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Re: [Declude.JunkMail] Gateways and CMDSPACE conundrum

2004-04-05 Thread Matt
Sandy,

I'm eagerly awaiting the results of your research :)

Thanks,

Matt

Sanford Whiteman wrote:

Matt,

Let  me  do  some  research  tonight;  it's  possible that I will have
something  tomorrow  that  will  let  you forward through the incoming
envelope  stuff  in  an  x-  header. (I shudder to think about the log
parsing alternative.)
--Sandy


Sanford Whiteman, Chief Technologist
Broadleaf Systems, a division of
Cypress Integrated Systems, Inc.
e-mail: [EMAIL PROTECTED]
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