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Article: 1209
From: Anthony Howe
Date: 2006-10-23 18:15:03 -0400
Subject: Re: Not Selecting the Best MX for Call-Back?

Removal...........: milters-request@milter.info?subject=remove
More information..: http://www.milter.info/#Support

Errol Neal wrote:
>>> [] Oct 23 13:23:19 mailscanner sendmail[5168]: 
>>> k9NHJJLk005168: Milter:
>>> from=<gshen@optionsgroup.com>, reject=550 5.7.1 MX 100 'mail.uu.net.'
>>> [] for <gshen@optionsgroup.com> not answering Oct 23 

>>> [root@mailscanner log]# host -t MX optionsgroup.com optionsgroup.com 
>>> mail is handled by 10 smtp.theoptionsgroup.com.
>>> tionsgroup.com mail is handled by 100 mail.uu.net.
>>> optionsgroup.com mail is handled by 5 smtp2.theoptionsgroup.com.

>> You should validate the lower MXes by hand first.
> They seem not to be responding.... Mind checking on your end? Smtp2
> quickly terminates the connection...

IN my case MX 5 answered and proves to be a dumb MX, which will result 
in milter-sender falling back on grey-listing. The other two never 
answered or took so long as to be useless, maybe tar pitting.

root@mx# telnet smtp2.theoptionsgroup.com 25
Connected to smtp2.theoptionsgroup.com.
Escape character is '^]'.
220 smtp2.theoptionsgroup.com ESMTP
helo mx.snert.net
250 smtp2.theoptionsgroup.com
mail from:<>
250 sender <> ok
rcpt to:<gshen@optionsgroup.com>
250 recipient <gshen@optionsgroup.com> ok
rcpt to:<bogus@optionsgroup.com>
250 recipient <bogus@optionsgroup.com> ok
221 smtp2.theoptionsgroup.com
Connection closed by foreign host.
root@mx# telnet smtp.theoptionsgroup.com 25
root@mx# telnet mail.uu.net 25

So I think milter-sender's original respons about the MXes not answering 
is correct, particularly if MX 5 is tar pitting, grey listing, 
auto-black listing, simply off-line at the moment, and or just playing 
dumb then your results will vary. If these are people you want to deal 
with, simple solution is to white list them through milter-sender:

	milter-sender-connect:theoptionsgroup.com	OK

A google search of theoptionsgroup.com shows references to some 
financial consulting group. They probably use Exchange, which is known 
to use in its default configuration an accept-then-bounce (dumb MX) policy.

Anthony C Howe          Skype: SirWumpus                    SnertSoft
+33 6 11 89 73 78         AIM: SirWumpus    Sendmail Milter Solutions
http://www.snert.com/     ICQ: 7116561

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