Mailing List SIMS@mail.stalker.com Message #15198
From: Christopher Bort <cbort@globalhomes.com>
Subject: Re: Reasonable Connection Timeout
Date: Thu, 30 Mar 2006 16:22:51 -0800
To: SIMS Discussions <SIMS@mail.stalker.com>
X-Mailer: Mailsmith 2.1.5 (Blindsider)
On 03/30/06 at 15:15, Warren Michelsen wrote:

> I'm having a problem with one company, a cable Internet provider,
> connecting to my mail server. They say it cannot be contacted, that
> connection attempts by their server to mine time out.
>
> How quickly should a server time out while waiting for a response
> from my server? What's a reasonable amount of time? Should a server
> give up if there's no response within the first 10 seconds?

Ten seconds is definitely unreasonably short. For one thing, these days
many SMTP servers intentionally delay sending their intial prompt in order
to weed out spambots that start issuing commands without waiting for the
prompt. My CommuniGate Pro server has it's prompt delay set to 25 seconds
for this reason, and CGPro drops connections where the sending MTA sends
commands before it sends its initial banner. Also, there are other reasons
why it might take significantly longer than 10 seconds for the initial
banner to be sent. IIRC, there's an RFC that has recommendations for SMTP
time-outs and it seems to me that the recommendation is several minutes (I
don't recall it exactly and don't have time to look it up at the moment).
The bottom line is that anyone silly enough to set a 10 second time out on
SMTP transactions is going to see a lot of messages not being delivered.

--
                   Christopher Bort | cbort@globalhomes.com
            Webmaster, Global Homes | webmaster@globalhomes.com
                      <http://www.globalhomes.com/>
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