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

[Matthew Galgoci <mgalgoci@redhat.com>]

I'd start by looking at the mail logs to see what it was trying to 
deliver. There may have been multiple messages (like from a high
volume list) which would rule out his theory about the retries being
too quick and against rfc.

On Mon, 18 Aug 2003, Christopher Faylor wrote:

> 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 -----
> 

-- 

Matthew Galgoci		"Dirty deeds, done dirt cheap"
System Administrator
Red Hat, Inc
919.754.3700 x44155