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From: pdb@sei.cmu.edu (Patrick Barron)
Newsgroups: comp.mail.misc
Subject: Re: Summary of mail-damage survey.
Message-ID: <3473@aw.sei.cmu.edu>
Date: Sat, 5-Dec-87 20:59:00 EST
Article-I.D.: aw.3473
Posted: Sat Dec  5 20:59:00 1987
Date-Received: Thu, 10-Dec-87 21:29:15 EST
References: <425@minya.UUCP>
Sender: netnews@sei.cmu.edu
Reply-To: pdb@sei.cmu.edu (Pat Barron)
Organization: Carnegie-Mellon University, SEI, Pgh, Pa
Lines: 39

In article <425@minya.UUCP> jc@minya.UUCP (John Chambers) writes:
>To end with a bit of levity:
>
>	==> Mailers that let "From:" addresses like "user@host.UUCP", 
>		"host!user", or "user@host.BITNET" escape on to the Internet 
>		without fixing the address (e.g., "user@host.UUCP" becomes 
>		"user%host.UUCP@gateway.do.main).
>  	==> Prepending "host!" to the From: lines of mail passing
>  		through the site and going out through UUCP.
>  
>Maybe I'm being weird, but I really can't see any end user getting 
>very excited about such things.

Since I was the one who mentioned the first point, I'll explain why it's
a really bad thing:  Suppose I'm on a machine that understands Internet/ARPANET
style mail addresses.  If I get a message that has (for instance) a "From:"
line containing "user@host.BITNET", and I try to use my mailer's "Reply"
command to reply to it, the message will be rejected by the mailer because
".BITNET" is not a valid domain.  Even worse, if the message can't be delivered
on the Internet side (because, for instance, the user on the destination
machine doesn't exist), the mail may not be returned to sender, but might
in fact end up in some "postmaster" mailbox somewhere, again because the
message didn't contain a valid "From:" address.

Sure, you can hack up your mailer to try and do something intelligent with
that sort of address, but such hacks can't always be depended on.  Under
BSD Unix, lots of people have rules in their sendmail.cf file to send all
".BITNET" mail to wiscvm.wisc.edu.  Well, in 10 days, all those mailers
are going to break, because wiscvm isn't going to be the gateway anymore.
The same thing happened with ".UUCP" mail, which a lot of people hardwired
to go to seismo.  When the plug was pulled, a lot of "end users" were real
upset because "this address that worked yesterday doesn't work today."

I guess the bottom line is that, if you're going to gateway mail to
the Internet from some other net, you had best make sure that you fix
the headers up to be in RFC 822 format, otherwise some mailer somewhere
down the line that you have no control over may choke on it.

--Pat.