[Exim] v6 delivery failure to exim 3.36

config is complex enough so that this one host is still
running 3.36. and it is a v4/v6 host. a v6 enabled
host is having delivery failures to me. i am seeing

2002-10-09 00:13:41 SMTP command timeout on connection from [2001:468:d01:8e:a00:20ff:fead:11d2]

the folk attempting delivery report as follows

From: Steve VanDevender <stevev@???>
To: Randy Bush <randy@???>
Cc: itojun@???
Subject: Re: mail stalling from darkwing/gladstone.uoregon.edu
Date: Wed, 9 Oct 2002 21:41:38 -0700

Randy Bush writes:
>> If there's something else you'd like me to try, I'll try it. I could
>> try running a tcpdump (we have the v6-enabled tcpdump) while manually
>> connecting over IPv6 to see if it comes up with anything enlightening.
>
> how about the actual smtp delivery failure. or run sendmail to
> deliver the message in debug mode.

What we have is stuff stalling in our mail queue because psg.com never
answers the EHLO.

Oct 9 12:55:54 darkwing sendmail[25663]: [ID 801593 mail.info]
g99JKr3d006674: to.<hervey@???>, delay.00:14:56, xdelay.00:05:01,
mailer.esmtp, pri.122037, relay.psg.com. [IPv6:2001:418:1::62],
dsn.4.0.0, stat.Deferred: 421 psg.com: SMTP command timeout - closing
connection

sendmail -v doesn't really shed much light on this:

/usr/lib/sendmail -Am -v randy@???
From: stevev@???
To: randy@???
Subject: test

testing 1 2 3

randy@???... Connecting to psg.com. via esmtp...
220 psg.com ESMTP Exim 3.36 #1 Wed, 09 Oct 2002 21:29:08 -0700
>>> EHLO darkwing.uoregon.edu

And that's all that happens with that.

If this helps, here's a tcpdump of a manual connection:

21:36:05.198402 darkwing.ipv6.uoregon.edu.36809 > 2001:418:1::62.smtp: S 1974368083:1974368083(0) win 25920 <nop,nop,sackOK,mss 1440>
21:36:05.568312 2001:418:1::62.smtp > darkwing.ipv6.uoregon.edu.36809: S 4212627811:4212627811(0) ack 1974368084 win 57344 <mss 1440>
21:36:05.568355 darkwing.ipv6.uoregon.edu.36809 > 2001:418:1::62.smtp: . ack 1 win 25920
21:36:06.095820 2001:418:1::62.2427 > darkwing.ipv6.uoregon.edu.ident: S 2562780208:2562780208(0) win 57344 <mss 1440,nop,wscale 0,nop,nop,timestamp 51057803 0>
21:36:06.095835 darkwing.ipv6.uoregon.edu.ident > 2001:418:1::62.2427: R 0:0(0) ack 2562780209 win 0
21:36:07.128239 2001:418:1::62.smtp > darkwing.ipv6.uoregon.edu.36809: P 1:65(64) ack 1 win 57600 [flowlabel 0x2ce0]
21:36:07.128459 darkwing.ipv6.uoregon.edu.36809 > 2001:418:1::62.smtp: . ack 65 win 25920
21:36:12.123219 darkwing.ipv6.uoregon.edu.36809 > 2001:418:1::62.smtp: P 1:28(27) ack 65 win 25920
21:36:15.491660 darkwing.ipv6.uoregon.edu.36809 > 2001:418:1::62.smtp: P 1:28(27) ack 65 win 25920
21:36:22.241625 darkwing.ipv6.uoregon.edu.36809 > 2001:418:1::62.smtp: P 1:28(27) ack 65 win 25920
21:36:26.738419 darkwing.ipv6.uoregon.edu.36809 > 2001:418:1::62.smtp: F 28:28(0) ack 65 win 25920
21:36:27.284661 2001:418:1::62.smtp > darkwing.ipv6.uoregon.edu.36809: . ack 1 win 57600 [flowlabel 0x2ce0]