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From: root@topaz.RUTGERS.EDU (Charles Root)
Newsgroups: net.mail,net.mail.headers
Subject: Re: Mail routing. Mail optimizing. Mail looping. mail breaking.
Message-ID: <4078@topaz.RUTGERS.EDU>
Date: Fri, 18-Oct-85 17:52:21 EDT
Article-I.D.: topaz.4078
Posted: Fri Oct 18 17:52:21 1985
Date-Received: Mon, 21-Oct-85 04:51:00 EDT
References: <3258@nsc.UUCP>
Organization: Rutgers Univ., New Brunswick, N.J.
Lines: 4
Keywords: arghhhh...
Xref: linus net.mail:1211 net.mail.headers:470

One useful convention is that if a message is from mailer-daemon, and
you get an error in trying to route it, just drop it on the floor.
Don't try to generate another error.  I would check the from field
for mailer-daemon or MAILER-DAEMON anywhere in the address.