Subject: SUN and the Content-Length header field

From: Tomas Kullman <[email-masked]>
Date: Wed, 22 Mar 1995 22:14:23 +0100

I have received complaints about the WU imap daemon trashing mail folders on
SUN systems. It is said to disregard the Content-Length: header field, which
is added at time of delivery. As a consequence of SUN making use of this
field, lines beginning with "From " are not quoted or prefixed. The daemon
is accused to split (presumably non-MIME) messages due to the existence of
the "From " lines.

I would like to hear any comments on this and suggestions to deal with this.

Regards,
--
Tomas Kullman <[email-masked]>
Embla Development Team
ICL ProSystems AB
SWEDEN

---

From: Rick Troth <[email-masked]>
Date: Wed, 22 Mar 1995 15:55:50 -0600 (CST)

> is accused to split (presumably non-MIME) messages due to the existence of
 
	Stamp out Content-Length headers in our lifetime. 

-- 
Rick Troth <[email-masked]>, Rice University, Information Systems 
http://is.rice.edu/~troth/

---

From: Mark Crispin <[email-masked]>
Date: Wed, 22 Mar 1995 14:39:59 -0800 (PST)

The claim is technically accurate, although I would not use that wording 
in describing the situation.

AT&T and SUN do not use standard Unix format mail.  Instead, they use
something that looks like Unix format mail, but depends upon an extremely
fragile and unrobust octet count.  Details are in a paper I wrote
"Content-Length Considered Harmful"; among other aspects of bad design
this count is generated by the originating MUA. 

It is technically infeasible to support Content-Length without making the
Unix format mail algorithms considerably slower and less robust.  What is
worse, on systems whose mailers do *not* use Content-Length, it would
become a security bug (actually, two different bugs).

The means to deal with this is, if you are using a SUN or AT&T system, to
replace the broken mail delivery agent invoked by sendmail (generally this
is /bin/mail) with a program that does the right thing, such as Steve
Hubert's sendit.  Many sites have done this and have reported good results.

I think that sendit is available for ftp'ing, but if not I'll look into
making it available. 

-- Mark --

DoD #0105, R90/6 pilot  FAX: (206) 842-0758  ICBM: N 47.36'24" W 122.34'08"
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