[postmaster@chiark.greenend.org.uk: [postmaster@sources.redhat.com] Excessive retries by your mail system]

[Christopher Faylor <cgf@redhat.com>]

Anyone have a clue on if this is correct and, if so, how to fix it?

cgf

----- Forwarded message from Ian Jackson as chiark postmaster <postmaster@chiark.greenend.org.uk> -----

From: Ian Jackson as chiark postmaster <postmaster@chiark.greenend.org.uk>
To: postmaster@sources.redhat.com
Subject: [postmaster@sources.redhat.com] Excessive retries by your mail system
Date: Wed, 13 Aug 2003 15:10:22 +0100

In the hour 1220-1320 UTC today (which I'm picking as a convenient
example), sources.redhat.com made 114 connections to my system
chiark.greenend.org.uk, 102 of which were rejected by my system with a
421 banner message (due to your system's excessive use of concurrent
SMTP sessions and its excessive history of SMTP errors when talking to
mine).

That's an average of one failed connection attempt every 35 seconds.
This is grossly excessive.  It's much faster than the retry rates
recommended in RFC1123 (Host Requirements).  It is also a much faster
retry rate than I have configured my system to permit to a single
calling site.

You are triggering capacity reservation and rate-limiting mechanisms
which are intended to cope with denial-of-service attacks and to slow
down spammers.  As a result the real mail which ought to be flowing
from your system to mine (various mailing lists hosted on
sources.redhat.com) is suffering delays.

Please could you reconfigure your system to retry much less often.
See RFC1123 s5.3.1.  Your system appears to be in violation (for
example) of the following paragraph, for example:

      The sender MUST delay retrying a particular destination
      after one attempt has failed.  In general, the retry
      interval SHOULD be at least 30 minutes; however, more
      sophisticated and variable strategies will be beneficial
      when the sender-SMTP can determine the reason for non-
      delivery.

When you've made your system stop hammering mine so much, the mail
should start flowing normally within an hour or two.

In the meantime you will probably not be able to reply by email.  If
you want to get in touch with me, please phone me on +44 1223 723614.
If I don't hear from you by this time tomorrow I'll try looking you up
in whois or the like.

Thanks for your attention.

Regards,
Ian Jackson.

----- End forwarded message -----