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Subject: Re: 1012 noops in a row cause slow responses from Postfix.
From: Wietse Venema (wietseporcupine.org)
Date: Fri Jun 23 2000 - 14:02:13 CDT

Mark Hoffman:
> My NT service (ick.) is maintaining a 24/7 connection to a bank of Postfix
> servers. The service is noop'ing every 2 seconds to maintain the connection,
> and to check that the connection is alive before sending out mail. When the
> commands sent to Postfix hit 1012, we get very slow response times. Has
> anyone else seen this? This has been a recent development in Postfix as the
> version I used in the middle of last year didn't exhibit this feature. Any
> help would be appreciated.

The limit is by default:

    smtpd_junk_command_limit = 1000

The SMTP server maintains a record of each session. The record is
reset after each successful delivery.

The limit on the number of junk commands prevents the session record
from consuming unbounded amounts of memory.

Sending NOOP every two seconds makes no sense. By default, Postfix
times out an idle connection after 300 seconds:

    smtpd_timeout = 300

I suggest you fix the NT client software.

        Wietse