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From: kyle@xanth.UUCP (Kyle Jones)
Newsgroups: comp.mail.headers,comp.bugs.4bsd
Subject: Re: sendmail hop count too low?
Message-ID: <2779@xanth.UUCP>
Date: Wed, 14-Oct-87 21:39:16 EDT
Article-I.D.: xanth.2779
Posted: Wed Oct 14 21:39:16 1987
Date-Received: Sat, 17-Oct-87 10:05:25 EDT
References: <2373@megaron.arizona.edu>
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In article <2373@megaron.arizona.edu>, whm@arizona.edu (Bill Mitchell) writes:
> Increasingly often I've seen mail returned because sendmail's hop count
> was exceeded by a valid sequence of hops.  As distributed on 4.3, the
> hop count (MAXHOP in conf.h) is 17 and I've seen a few sendmails that
> have a hop count of 15.  Unfortunately, this isn't enough -- some Internet
> mail endpoints are more than 17 hops apart.  I don't know that there's
> any solution for this other than to raise the hop count (which is non-trivial
> for binary-only sites).

I thought sendmail sources were available for everyone from
ucbarpa.berkeley.edu.  Is this no longer the case?

Sendmail checks the hop count by noting the number of Received:
headers in a message.  One way to reduce the number of Received:
headers is to compact them as a message moves from one organizational
domain to the next.

For example, suppose a message is delivered to megastron.arizona.edu
with the following Received headers:

Received: from nansen.ocean.odu.edu by xanth.cs.odu.edu with SMTP 
	(5.51/odu-gateway) id AA24116; Wed, 14 Oct 87 21:04:25 EDT
Received: from laplace.ocean.odu.edu by nansen.ocean.odu.edu with SMTP 
	(5.51/odu-lanleaf) id AA00238; Wed, 14 Oct 87 21:04:07 EDT
Received: from ICASE.ARPA by laplace.ocean.odu.edu with SMTP
	(5.51/odu-lanleaf) id AA03459; Wed, 14 Oct 87 21:03:45 EDT
Received: by ICASE.ARPA (4.7/1.2a) id AA27641; Wed, 14 Oct 87 21:00:07 edt

Before handing the message to sendmail, a program on megastron could
crush thees headers down to:

Received: from ICASE.APRA by odu.edu with SMTP
	id AA03459; Wed, 14 Oct 87 21:08:05 EDT
Received: by ICASE.ARPA (4.7/1.2a) id AA27641; Wed, 14 Oct 87 21:00:07 edt

This would stamp out the redundant information in the headers tacked
on by hosts within the same organization.  For such a program to be most
effective, hosts would have to use the proper format for Received:
headers (some don't).

kyle jones  <kyle@odu.edu>  old dominion university, norfolk, va  usa