Problem receiving list email: timeout waiting for input

[J M Cerqueira Esteves]

Greetings

I have been mostly unable to receive email from the FSF Europe
Discussion list, and maybe this is happening to others as well.  I get
lots of entries like

 timeout waiting for input from mail-ffm-p.arcor-ip.de during message collect

on the machine receiving email.

Eventually we get  30 (=MaxDaemonChildren) open sendmail connections,
and sendmail stops accepting other connections.  This is now happening
several times per day.  A few days ago, I contacted postmaster at mail.arcor-ip.de
about this but received no reply (perhaps because of the same problem :) ).

Following a suggestion in 
  http://www.sendmail.org/faq/section3.html#3.10
I added 
  define(`confTO_IDENT',`0s')dnl
to our sendmail.mc and some mail from the list arrived, but I now
assume there was some coincidence (either that or the postmaster
took some temporary corrective measure), since things are now as before.
Anyway, I noticed that our IDENT timeout before was just 30s...

I still believe that there may be some problem on the sending side.  This has
never happened to us with email from other sources, as far as I know.
Could it be some firewall in there, maybe something related to "path MTU
discovery" as discussed in
 http://www.sendmail.org/faq/section3.html#3.10 ?

I found this at Google Groups, in thread
http://groups.google.com/groups?hl=en&lr=&safe=off&ic=1&th=14f485307e78d8ff,3&seekm=fNcq4.45623%24ox5.11953350%40tw11.nn.bcandid.com#p
 
  From: Tom Simpson (wtsimpson at my-deja.com)
  Subject: Re: redhat linux 6.x and sendmail8..9.3 
  Newsgroups: comp.mail.sendmail
  Date: 2000/02/17 

  [...]

  Also from the router side IF it is a Cisco router Check the Version OF
  IOS and MAKE sure that there is not any problems with the release that
  you have. I know from personnal experince that anything below 12.07 has
  problems that cause NAT issues on the 3600 series at least. After a few
  days the memory gets eatten up by memory leaks and the ftp services
  stop functioning through the routers, after setting up NAT, they worked
  fine when we had public IP's on both sides of the routers. (along with
  who knows what else). After flashing the 3600's to 12.09 from 12.05 &
  12.06 ALOT of the problems went away for now on transfering through the
  router. So this could be a problem to look at as well. IF you have
  access to a Server(root access that is) run a TCP dump on the outside
  when you try to send something out, This might help show you where your
  problem may be. Also watch the NAT translations at the router, on Cisco
  the enable command is show ip nat trans . This way you can verify that
  the router is passing the traffic back and forth. Also check to see IF
  any access-lists are on the interfaces that MIGHT be setup to timeout
  connections as well.

Please contact me if you find a possible cause for this problem; maybe
others are also affected, not only unable to read list email but also getting
their sendmail systems blocked from receiving other messages.
It would be best if you email me through another route in order to ensure
that your message reaches me...

Meanwhile, I'll have to remove myself (temporarily, I hope) from the
FSF Europe Discussion mailing list, and if mail-ffm-p.arcor-ip.de
insists on lots of retries I may have to filter SMTP traffic from it to
artenumerica.com in order to avoid sendmail blocking.

Best regards and thank you in advance

                     J Esteves

-- 
 jmce:  +351 919838775   ~  http://jmce.artenumerica.org/