Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxn!ihnp4!cbosgd!mark
From: mark@cbosgd.UUCP (Mark Horton)
Newsgroups: net.mail
Subject: Re: Neighbor optimized away
Message-ID: <2065@cbosgd.UUCP>
Date: Wed, 30-Apr-86 14:25:23 EDT
Article-I.D.: cbosgd.2065
Posted: Wed Apr 30 14:25:23 1986
Date-Received: Fri, 2-May-86 10:21:13 EDT
References: <4509@dartvax.UUCP>
Organization: AT&T Bell Laboratories, Columbus, Oh
Lines: 35

smail has a feature similar to what you describe.  In sendmail.cf, it
reads in L.sys and turns any mail to systems in L.sys into a direct
request to go to that hop next.  Thus, if sfmag is in L.sys and mcvax
isn't, it will turn
	user@sfmag.uucp	=> smail sfmag!user
	user@mcvax.uucp	=> smail mcvax.uucp!user
smail looks up the latter in the domain database, the former goes direct.

This helps for local mail but not if you're trying to reoptimize paths
of mail going through your machine.

By the way, this feature bit me recently.  cbosgd can't dial out (telco
has broken our phone lines for the past 6 weeks) so most of L.sys is
links to places we can't get to.  I redid pathalias to go via datakit,
but this overrode it for hosts in L.sys.

Here are some related parts of our sendmail.cf:

# Preemptive ether and UUCP connections.  We prefer these connections 
# over both designated transport mechanisms and the general depository.

FU/usr/lib/uucp/L.sys %s

# Preemption: for a host on a known link turn the domain spec into a
# mock domain indicating the link.  One set of these rules for each of 
# the F classes listed in the local configuration options.

R$*<$*$=U.$D>$*			$:$1<$2$3.UUX>$4	uuxhost.mydomain
R$*<$*$=U.$=D>$*		$:$1<$2$3.UUX>$5	uuxhost.anydomain
R$*<$*$=U.$A>$*			$:$1<$2$3.UUX>$4	uuxhost.anotherdomain
R$*<$*$=U.$=T>$*		$:$1<$2$3.UUX>$5	uuxhost.mock-domain
R$*<$*$=U>$*			$:$1<$2$3.UUX>$4	uuxhost

# Designated delivery:
R$*<@$=U.UUX>$*		$#uux$@$2$:$1$3			known uucphost