Mailing List SIMS@mail.stalker.com Message #14777
From: Bill Cole <listbill@scconsult.com>
Subject: Re: outlook clients, POP times out?
Date: Wed, 29 Sep 2004 23:32:09 -0400
To: SIMS Discussions <SIMS@mail.stalker.com>
At 9:18 PM -0400 9/29/04, Charles Mangin  imposed structure on a stream of electrons, yielding:
bill -

do you mind if i quote your response as an expert on this issue, verbatim, to the client, who is now telling me that it must be my fault, and that their previous isp never had any trouble like this?

I have no problem with that, as long as you include the caveat that I have not looked at your system directly, so I don't know all of the possible issues.


frankly, i'm ready to call it an outlook issue - which it seems to be - and be done with it. use eudora or mozilla or anything else, please... every time i have to deal with an issue, it's a client with outlook express.

That does seem to be the way it goes...

There is one more possible source of this trouble, but it would cause all large messages to have problems, not just those with attachments. Many systems use a mechanism called "Path MTU Discovery" to work out the largest packet size that can be sent end-to-end on a connection, so that the session can be tuned to hit optimal performance. That mechanism (which is done in the deeper layers of the network protocol stack, and I believe is on by default on all MacOS versions) conflicts with people doing dumb things on firewalls, specifically the all-too-common practice of dropping all ICMP packets. This is most common with users on DSL or cable modem connections running "personal firewall" software that is misconfigured, but it can be seen in other setups as well. Usually you can eliminate this as a possible cause by testing with 'ping' in both directions: if both ends can get ping responses from the other end, then there is nothing in between dropping ICMP completely.



--
Bill Cole                                  bill@scconsult.com

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