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Re: 2.99.50s19 smtp & hotmail.com



David S. Miller wrote:
> Just a note, hotmail uses a funny rate limiting device in front of
> their machines which directly messes with TCP header contents and does
> other nasty things.
> 
> This appliance has bugs, and Linux was able to trigger it, the most
> problematic seems to be TCP timestamps.  The appliance aparently has
> some bug workaround for BSDi which occaisionally sets the packet
> length wrong when timestamps are used, the appliance "adjusts" the
> packet length to try to fix the bug in BSDi.  It seems to break
> connections to clients who do TCP timestamps correctly.

	Oddly I see these problems at Solaris 2.5.1 boxes,
	and at DEC Tru64 4.0D.

	(I don't only mean smtp stuck into OF=0 state for long
	 time, but apalling smtp throughput in overall!)

	I sent email to  <postmaster@hotmail.com>  and a few other
	addresses, but those M$ morons seem to have auto-answer
	services at all addresses.

	Using QMail's approach of launching all messages as separate
	sessions would deliver everything, but for all smart recipients
	PIPELINING is far better approach -- and less strenuous to
	the network.

	I wonder what hacker friendly forum would be usefull for
	spreading knowledge that Hotmail.COM has serious email
	receiving problems...  Something which also M$/Hotmail
	pays attention to..  ZDnet ???

	Some interesting extracts from logs are added below.
	They have a widely varying array of servers with different
	software versions, and different BUGS/misfeatures.

	They e.g. implement incoming message size limit, but they
	don't claim to implement ESMTP (except when they claim to
	do it in connection banner, they don't do EHLO...  IF they
	did EHLO, they could do SIZE in that banner and pre-block
	too large a messages..  Of course EHLO is prerequisite
	for PIPELINING, which would allow faster feed, but they don't
	want to do that if they want to limit input speeds the way
	they are doing now...  Oh yes, some servers yield 4** code
	for nonexistent accounts, others yield 5**.)

> Later,
> David S. Miller
> davem@redhat.com

	/Matti Aarnio

	------------
#       (Connecting to `mail5.hotmail.com' [216.33.151.135|25] Thu Jun 24 18:07:06 1999)
r       220-HotMail (NO UCE) ESMTP server ready at Thu Jun 24 08:07:06 1999 
r       220 ESMTP spoken here
w       EHLO smtp.tele.fi
r       500 Syntax error, command unrecognized
	------------
w       HELO smtp.tele.fi
r       250 Requested mail action okay, completed
w       MAIL From:<xxx@yyy.com>
r       250 Requested mail action okay, completed
w       RCPT To:<zzzz@hotmail.com>
r       450 Requested mail action not taken: mailbox unavailable.
	------------
#       (Connecting to `mail.hotmail.com' [209.1.112.253|25] Thu Jun 24 18:07:07 1999)
r       220-HotMail (NO UCE) ESMTP server ready at Thu Jun 24 08:07:27 1999 
r       220 ESMTP spoken here
w       EHLO smtp.tele.fi
r       500 Syntax error, command unrecognized
w       HELO smtp.tele.fi
#       (closed SMTP channel - hangup on smtpwrite() )
	------------
#       (Connecting to `mail3.hotmail.com' [216.32.182.252|25] Thu Jun 24 18:07:35 1999)
r       220 law2-m76.hotmail.com Server SMTP ready at Thu, 24 Jun 1999 08:07:45 +0100
w       EHLO smtp.tele.fi
r       550 Unknown command 'EHLO'
w       HELO smtp.tele.fi
r       250 law2-m76.hotmail.com Hello smtp.tele.fi
	------------