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Re: [Asrg] Some data on the validity of MAIL FROM addresses

Scott Nelson <scott@spamwolf.com> Mon, 19 May 2003 02:03 UTC

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From: Scott Nelson <scott@spamwolf.com>
Subject: Re: [Asrg] Some data on the validity of MAIL FROM addresses
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Date: Sun, 18 May 2003 19:01:24 -0700

At 08:58 PM 5/18/03 -0400, Kee Hinckley wrote:
>At 10:53 AM +0100 5/18/03, Jon Kyme wrote:
>>  >
>>>  Interesting that the results vary so much by ISP.  Yahoo accounts are
>>>  pretty valid.  Hotmail accounts are pretty bad.  AOL is quite good.
>>>  Earthlink has a problem.  MSN's slightly better, but still negative.
>>
>>
>>Of course yahoo will say 250 to pretty much anything.
>>So these addresses are "valid" in what sense exactly?
>
>They said "no" to 16% of the messages I queried them on.  The 
>specific message they used was:
>
>553 VS10-RT Possible forgery or deactivated due to abuse (#5.1.1)
>
>Can you show instances in which they say yes to messages they cannot deliver?
>

I tried this:

% head /dev/urandom | md5sum
ce4c096d881440fffebbde3b64291d92  -

% telnet mx1.mail.yahoo.com 25
Trying 64.156.215.5...
Connected to mx1.mail.yahoo.com.
Escape character is '^]'.
220 YSmtp mta124.mail.scd.yahoo.com ESMTP service ready
helo spamwolf.com
250 mta124.mail.scd.yahoo.com
mail from:<>
250 null sender <> ok
rcpt to:<ce4c096d881440fffebbde3b64291d92@yahoo.com>
250 recipient <ce4c096d881440fffebbde3b64291d92@yahoo.com> ok
quit
221 mta124.mail.scd.yahoo.com
Connection closed by foreign host.


Saying that <ce4c096d881440fffebbde3b64291d92@yahoo.com> is 
unlikely to be a valid address is an understatement.

Scott Nelson <scott@spamwolf.com>
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