Mailing List SIMS@mail.stalker.com Message #15458
From: Bill Cole <listbill@scconsult.com>
Subject: Re: .Mac problems
Date: Fri, 23 Feb 2007 14:08:03 -0500
To: SIMS Discussions <SIMS@mail.stalker.com>
At 10:25 AM -0800 2/23/07, Michael Heth  imposed structure on a stream of electrons, yielding:
Hey Folks,

I have been having problems with people sending to my SIMS servers from .MAC accounts. This started about a month ago. Has anyone else seen this? Here is an error message a user received. Although the one below shows "delayed", these messages never do get through. I do not have any timeout problems with my server even though the error messages says the send timed out.

Thanks for any tips/info.

M./


Hi Marty,
I tried replying with my .mac address and here is the error message I got..
-Armando Quintero
  **********************************************
    **      THIS IS A WARNING MESSAGE ONLY      **
    **  YOU DO NOT NEED TO RESEND YOUR MESSAGE  **
    **********************************************

The original message was received at Thu, 22 Feb 2007 07:50:05 -0800 (PST)
from smtpin05-en2 [10.13.10.150]

   ----- Transcript of session follows -----
451 4.4.1 reply: read error from anvil.serversmiths.com.
<marty@martyknapp.com>... Deferred: Operation timed out with anvil.serversmiths.com.
Warning: message still undelivered after 4 hours
Will keep trying until message is 4 days old
Reporting-MTA: dns; smtpout.mac.com
Arrival-Date: Thu, 22 Feb 2007 07:50:05 -0800 (PST)



Troubleshooting this from your end requires you to look at your logs from around  that time looking for connections that might have been from the .mac server farm, which I believe are all using 17.250.* addresses. The error message implies that the sending side got tired of waiting for a response from your machine, although it does specify the point of the transaction it was having trouble with.

One problem many people have had recently has been caused by not noticing when DNSBL's [0] go out of service.  The most recent example is the ordb.org list. The result of continuing to query such services when they have stopped serving up any data can be a very slow failure, as the DNS queries time out. SIMS is particularly subject to this as a problem because it seems to do DNSBL lookups serially, and timeouts can get very long if you have your machine configured for multiple DNS servers.

More broadly, slow response problems with SIMS are frequently caused by DNS issues. SIMS does DNSBL checks at connect time before sending the banner, an A lookup before responding to HELO/EHLO, and a full MX resolution on the domain part of the MAIL FROM argument, and if you have a slow DNS server (or a dead one) configured on the system running SIMS, you can  make the SIMS response slow.


[0] SIMS' config refers to DNSBL's as "RBL's" but technically "RBL" refers only to the MAPS Realtime Blackhole List, the first such DNS-Based List or DNSBL.
--
Bill Cole                                  bill@scconsult.com

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