327 lines
14 KiB
HTML
327 lines
14 KiB
HTML
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
|
||
|
|
<!-- $Id: reply-to-harmful.html,v 1.20 2002/11/15 03:46:04 chip Exp $ -->
|
||
|
|
<HTML>
|
||
|
|
<HEAD>
|
||
|
|
<TITLE>"Reply-To" Munging Considered Harmful</TITLE>
|
||
|
|
</HEAD>
|
||
|
|
|
||
|
|
<BODY BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#5500EE" ALINK="#FF0000" VLINK="#551A8B">
|
||
|
|
|
||
|
|
<h1>This Page is a Mirror</h1>
|
||
|
|
<p>This page has been mirrored for historical preservation</p>
|
||
|
|
<hr>
|
||
|
|
|
||
|
|
<H1>"Reply-To" Munging Considered Harmful</H1>
|
||
|
|
<H2>An Earnest Plea to Mailing List Administrators</H2>
|
||
|
|
<HR>
|
||
|
|
|
||
|
|
<P>An email message requires some amount of processing when it is
|
||
|
|
redistributed to a mailing list. At the very least, the envelope must
|
||
|
|
be rewritten to redirect bounces directly to the list administrator.
|
||
|
|
While the message is being processed, the list administrator might
|
||
|
|
take advantage of the opportunity to
|
||
|
|
<A HREF="http://www.fwi.uva.nl/~mes/jargon/m/munge.html">munge</A> some
|
||
|
|
of the message headers.
|
||
|
|
|
||
|
|
<P>Some forms of header munging are helpful, such as special loop-detection
|
||
|
|
headers. Others are questionable. Most are ill-advised or dangerous.
|
||
|
|
Many list adminstrators want to add a <KBD>Reply-To</KBD> header that
|
||
|
|
points back to the list. This transformation also is one of the most
|
||
|
|
ill-advised.
|
||
|
|
|
||
|
|
<P>Some administrators claim that <KBD>Reply-To</KBD> munging makes
|
||
|
|
it easier for users to respond to the entire list, and helps encourage
|
||
|
|
list traffic. These benefits are fallacious. Moreover, <KBD>Reply-To</KBD>
|
||
|
|
can have harmful -- even dangerous -- effects. If you think
|
||
|
|
<KBD>Reply-To</KBD> munging is a good idea, I hope I can change your
|
||
|
|
mind.
|
||
|
|
|
||
|
|
<H2>The Principle of Minimal Munging</H2>
|
||
|
|
|
||
|
|
<P>Email processing is pretty tricky. Read through
|
||
|
|
<A HREF="ftp://ftp.isi.edu/in-notes/rfc822.txt">RFC-822</A>, the
|
||
|
|
<CITE>Standard for the Format of ARPA Internet Text Messages</CITE>,
|
||
|
|
sometime. It is 47 pages of dense, dry detail. A lot of engineering
|
||
|
|
and consideration went into this work. Even still, RFC-822 leaves
|
||
|
|
many corner conditions and specialized circumstances poorly specified.
|
||
|
|
<A HREF="ftp://ftp.isi.edu/in-notes/rfc1123.txt">RFC-1123</A>, the
|
||
|
|
commonly-called <CITE>Internet Host Requirements</CITE> document, adds
|
||
|
|
a couple dozen more pages, and remedies some of the defects. Then
|
||
|
|
there is MIME, X.400 mapping, and a handful of other standards and
|
||
|
|
conventions -- some documented and some folklore. Email handling is
|
||
|
|
surprisingly complicated, and even an innocuous-sounding change might
|
||
|
|
have grave, unintended consequences.<P>
|
||
|
|
|
||
|
|
<P>The "Principle of Minimal Munging" is a good rule that will keep
|
||
|
|
you out of trouble. It says you should <EM>not</EM> make any changes
|
||
|
|
to an email header unless you know precisely what you want to do,
|
||
|
|
why you want to do it, and what it will affect. Unless you can
|
||
|
|
articulate a clear reason for munging and understand the full consequences
|
||
|
|
of the action, you should not do it.
|
||
|
|
|
||
|
|
<P>The "Principle of Minimal Munging" will help you avoid the sorts of
|
||
|
|
problems we are about to discuss. This principle <EM>is</EM> a rule
|
||
|
|
designed to be broken, but you can avoid some significant heartache
|
||
|
|
by thinking hard and long before you do so.
|
||
|
|
|
||
|
|
<H2>It Adds Nothing</H2>
|
||
|
|
|
||
|
|
<P><KBD>Reply-To</KBD> munging does not benefit the user with a reasonable
|
||
|
|
mailer. People want to munge <KBD>Reply-To</KBD> headers to make
|
||
|
|
"reply back to the list" easy. But it already is easy. Reasonable
|
||
|
|
mail programs have two separate "reply" commands: one that replies
|
||
|
|
directly to the author of a message, and another that replies to the
|
||
|
|
author plus all of the list recipients. Even the lowly
|
||
|
|
<A HREF="http://www.bsdi.com/bsdi-man/?Mail%281%29">Berkeley
|
||
|
|
<CITE>Mail</CITE></A> command has had this for about a decade.
|
||
|
|
|
||
|
|
<P>Any reasonable, modern mailer provides this feature. I prefer the
|
||
|
|
<A HREF="http://www.myxa.com/myxa/elm.html"><CITE>Elm</CITE> mailer</A>.
|
||
|
|
It has separate "r)eply" and "g)roup-reply" commands. If I
|
||
|
|
want to reply to the author of a message, I strike the "<KBD>r</KBD>"
|
||
|
|
key. If I want to send a reply to the entire list, I hit "<KBD>g</KBD>"
|
||
|
|
instead. Piece 'o cake.
|
||
|
|
|
||
|
|
<P>I mention <CITE>Elm</CITE> here (and a lot later on) simply because
|
||
|
|
that's the mailer I use everyday. This sort of support is not unique
|
||
|
|
to <CITE>Elm</CITE> Any reasonable mailer provides it. The
|
||
|
|
<CITE>Pine</CITE> mailer, for instance, asks directly, "Reply to all
|
||
|
|
recipients?" when you use the "<KBD>r</KBD>" command. It doesn't
|
||
|
|
get much easier than that!
|
||
|
|
|
||
|
|
<P>Whichever mailer you choose, please <EM>read</EM> the fine manual
|
||
|
|
that comes with it. Unless you are stuck with some decrepit mail
|
||
|
|
system, I bet you'll find it has a similar feature. If so, you easily
|
||
|
|
can choose to direct your responses either to the original author or
|
||
|
|
the entire list. Mauling the mail headers doesn't make it any easier.
|
||
|
|
|
||
|
|
<H2>It Makes Things Break</H2>
|
||
|
|
|
||
|
|
<P>If you use a reasonable mailer, <KBD>Reply-To</KBD> munging does not
|
||
|
|
provide any new functionality. It, in fact, <EM>decreases</EM>
|
||
|
|
functionality. <KBD>Reply-To</KBD> munging destroys the "reply-to-author"
|
||
|
|
capability. Munging makes this command act effectively the same as
|
||
|
|
the "reply-to-group" function. We haven't added anything new, we've
|
||
|
|
only taken away. <KBD>Reply-To</KBD> munging is not merely benign,
|
||
|
|
it is harmful. It renders a useful mail capability inoperative.
|
||
|
|
|
||
|
|
<H2>Freedom of Choice</H2>
|
||
|
|
|
||
|
|
<P>Some administrators justify <KBD>Reply-To</KBD> munging by saying,
|
||
|
|
"All responses should go directly to the list anyway." This is
|
||
|
|
arrogant. You should allow <EM>me</EM> to decide exactly how I wish
|
||
|
|
to respond to a message. If I feel a public response is justified,
|
||
|
|
I'll hit the "<KBD>g</KBD>" key and tell <CITE>Elm</CITE> to do a
|
||
|
|
group-reply. If I believe a private response is more appropriate,
|
||
|
|
I'll use "<KBD>r</KBD>" to send one. Please allow me the freedom
|
||
|
|
to decide how to handle a message.
|
||
|
|
|
||
|
|
<H2>Can't Find My Way Back Home</H2>
|
||
|
|
|
||
|
|
<P>It may be impossible to reply to the author of a message once the
|
||
|
|
<KBD>Reply-To</KBD> header is munged. The <KBD>Reply-To</KBD> header
|
||
|
|
was not invented on a whim. It is there for the sender of a mail
|
||
|
|
message to use. If you stomp on this header, you can lose important
|
||
|
|
information.
|
||
|
|
|
||
|
|
<P>There are good reasons why the sender might insert a <KBD>Reply-To</KBD>
|
||
|
|
header. The sender might <EM>not</EM> be the original author of the
|
||
|
|
message (the name that appears in the <KBD>From</KBD> header). If
|
||
|
|
responses should return to the sender and not the original author,
|
||
|
|
then the sender will insert a <KBD>Reply-To</KBD> header. Or, maybe
|
||
|
|
the sender added a <KBD>Reply-To</KBD> because he or she cannot receive
|
||
|
|
email at the account from which the message was sent. There are many
|
||
|
|
good reasons to place a <KBD>Reply-To</KBD> header into a mailing list
|
||
|
|
message.
|
||
|
|
|
||
|
|
<P>If the <KBD>Reply-To</KBD> is munged by the mailing list, the value
|
||
|
|
provided by the original sender is lost. <KBD>Reply-To</KBD> munging
|
||
|
|
can make it impossible to reach the sender of a message.
|
||
|
|
|
||
|
|
<H2>Coddling the Brain-Dead, Penalizing the Conscientious</H2>
|
||
|
|
|
||
|
|
<P>There are, unfortunately, poorly implemented mail programs that lack
|
||
|
|
separate reply-to-author and reply-to-group functions. A user saddled
|
||
|
|
with such a brain-dead mailer can benefit from <KBD>Reply-To</KBD>
|
||
|
|
munging. It makes it easier for him or her to send responses directly
|
||
|
|
to the list.
|
||
|
|
|
||
|
|
<P>This change, however, penalizes the conscientious person that uses
|
||
|
|
a reasonable mailer. This is a poor trade-off. As Internet list
|
||
|
|
administrators, we should encourage people to run reasonable software.
|
||
|
|
If a few people need to type in a full reply address so that everybody
|
||
|
|
else can use all the features of their mailer, I say, "Fine!" We
|
||
|
|
should not penalize the conscientious to coddle those who run brain-dead
|
||
|
|
software.
|
||
|
|
|
||
|
|
<H2>Principle of Least Work</H2>
|
||
|
|
|
||
|
|
<P>Compare and contrast: the work required for me (or any other
|
||
|
|
<CITE>Elm</CITE> user) to reply on lists that do and don't employ
|
||
|
|
<KBD>Reply-To</KBD> munging.
|
||
|
|
|
||
|
|
<BLOCKQUOTE>
|
||
|
|
<PRE>
|
||
|
|
Case One: Case Two:
|
||
|
|
Action Without Munging With Munging
|
||
|
|
============= ===================== =====================
|
||
|
|
|
||
|
|
Reply to Hit the "g" Probably hit the "r"
|
||
|
|
everybody. key. key, but maybe the "g"
|
||
|
|
key if there were other
|
||
|
|
recipients of the message.
|
||
|
|
|
||
|
|
Reply just Hit the "r" Look at the original
|
||
|
|
to author. key. message header, write
|
||
|
|
down the sender's
|
||
|
|
email address, hit the
|
||
|
|
"r" key, call up the
|
||
|
|
header editing menu,
|
||
|
|
erase the current To:
|
||
|
|
value, and type in the
|
||
|
|
sender's full email
|
||
|
|
address. And pray the
|
||
|
|
correct address wasn't
|
||
|
|
wiped out when the Reply-To
|
||
|
|
was munged.
|
||
|
|
</PRE>
|
||
|
|
</BLOCKQUOTE>
|
||
|
|
|
||
|
|
<P>Again, your preferred mailer probably implements this feature in
|
||
|
|
a different fashion. Nonetheless, it should be easy. I'll take box
|
||
|
|
number one, Monte.
|
||
|
|
|
||
|
|
<H2>Principle of Least Surprise</H2>
|
||
|
|
|
||
|
|
<P>When I hit the "<KBD>r</KBD>" key in <CITE>Elm</CITE>, it sends a
|
||
|
|
response to the author of a message. When you munge the <KBD>Reply-To</KBD>
|
||
|
|
header you change this action so that it does something entirely
|
||
|
|
different from what I expect. This creates specialized behavior for
|
||
|
|
your mailing list, which increases the potential for surprise. I'm
|
||
|
|
not schooled in the science of human factors, but I suspect surprise
|
||
|
|
is not an element of a robust user interface.
|
||
|
|
|
||
|
|
<P>Private messages frequently are broadcast across lists that do
|
||
|
|
<KBD>Reply-To</KBD> munging. That's an empirical fact. It's what
|
||
|
|
happens when you violate the principle of least surprise.
|
||
|
|
|
||
|
|
<H2>Principle of Least Damage</H2>
|
||
|
|
|
||
|
|
<P>Consider the damage when things go awry. If you do not munge the
|
||
|
|
<CITE>Reply-To</CITE> header and a list subscriber accidentally sends a
|
||
|
|
response via private email instead of to the list, he or she has to
|
||
|
|
follow up with a message that says, "Ooops! I meant to send that to
|
||
|
|
the list. Could you please forward a copy for me." That's a hassle,
|
||
|
|
and it happens from time to time.
|
||
|
|
|
||
|
|
<P>What happens, however, when a person mistakenly broadcasts a private
|
||
|
|
message to the entire list? If the message is a complaint about the
|
||
|
|
personal hygiene of sender's boss, or the sex life of his or her
|
||
|
|
roommate, a simple "Ooops!" won't cut it. About all you can do is
|
||
|
|
send a followup with lots of retroactive smileys (weak). Or say your
|
||
|
|
cat was dancing on the keyboard (better). Or start reading the
|
||
|
|
classifieds for a new job/roommate/set of teeth (most likely).
|
||
|
|
|
||
|
|
<P><KBD>Reply-To</KBD> munging encourages catastrophic failure modes.
|
||
|
|
Sure, you don't need <KBD>Reply-To</KBD> munging to create this sort
|
||
|
|
of damage. A simple slip of the fingers will suffice. When, however,
|
||
|
|
you violate the "Principle of Least Surprise" you invite this sort
|
||
|
|
of disaster. A responsible list administrator will avoid creating
|
||
|
|
avenues that lead to such extreme damage.
|
||
|
|
|
||
|
|
<H2>And in the End...</H2>
|
||
|
|
|
||
|
|
<P>If you are not convinced yet, then allow me one final plea. I contribute
|
||
|
|
to the <CITE>Elm</CITE> mailer development team. I get to see a lot
|
||
|
|
of the wants and requests from the user community. Guess what feature
|
||
|
|
more and more people are asking for? A <EM>third</EM> reply command
|
||
|
|
-- one that ignores any existing <KBD>Reply-To</KBD> header! Want to
|
||
|
|
guess why people are asking for it? If you think you are doing your
|
||
|
|
subscribers a service by munging <KBD>Reply-To</KBD> headers, you are
|
||
|
|
kidding yourself. You are making your subscribers miserable.
|
||
|
|
|
||
|
|
<P>Some list administrators, even after reading all this, seem to say,
|
||
|
|
"Oh, it's not that bad. Besides, my subscribers like it!" If they
|
||
|
|
do, it's probably because they haven't bothered to learn to use the
|
||
|
|
"reply-to-group" feature of their mailer. Instead of going through
|
||
|
|
all the trouble of making your list gateway scribble on email headers,
|
||
|
|
how about making an effort to educate your subscribers?
|
||
|
|
|
||
|
|
<H2>Summary</H2>
|
||
|
|
|
||
|
|
<P>Many people want to munge <KBD>Reply-To</KBD> headers. They believe
|
||
|
|
it makes reply-to-list easier, and it encourages more list traffic.
|
||
|
|
It really does neither, and is a very poor idea. <KBD>Reply-To</KBD>
|
||
|
|
munging suffers from the following problems:
|
||
|
|
|
||
|
|
<UL>
|
||
|
|
|
||
|
|
<LI>It violates the principle of minimal munging.
|
||
|
|
|
||
|
|
<LI>It provides no benefit to the user of a reasonable mailer.
|
||
|
|
|
||
|
|
<LI>It limits a subscriber's freedom to choose how he or she will direct
|
||
|
|
a response.
|
||
|
|
|
||
|
|
<LI>It actually reduces functionality for the user of a reasonable mailer.
|
||
|
|
|
||
|
|
<LI>It removes important information, which can make it impossible to
|
||
|
|
get back to the message sender.
|
||
|
|
|
||
|
|
<LI>It penalizes the person with a reasonable mailer in order to coddle
|
||
|
|
those running brain-dead software.
|
||
|
|
|
||
|
|
<LI>It violates the principle of least work because complicates the
|
||
|
|
procedure for replying to messages.
|
||
|
|
|
||
|
|
<LI>It violates the principle of least surprise because it changes the
|
||
|
|
way a mailer works.
|
||
|
|
|
||
|
|
<LI>It violates the principle of least damage, and it encourages a failure
|
||
|
|
mode that can be extremely embarrassing -- or worse.
|
||
|
|
|
||
|
|
<LI>Your subscribers don't want you to do it. Or, at least the ones who
|
||
|
|
have bothered to read the docs for their mailer don't want
|
||
|
|
you to do it.
|
||
|
|
|
||
|
|
</UL>
|
||
|
|
|
||
|
|
<H2>Addendum</H2>
|
||
|
|
|
||
|
|
<P>In case you are wondering, yes, I once thought <KBD>Reply-To</KBD> munging
|
||
|
|
was a nifty idea. I got better though.
|
||
|
|
|
||
|
|
<P>When I started running email lists, I munged 'em all. One day I
|
||
|
|
accidentally sent a private, personal reply out over one of my own
|
||
|
|
damn lists. If the list owner can't remember how to use the list
|
||
|
|
properly, no way will the subscribers be able to sort it out. I
|
||
|
|
stopped munging the very next day.
|
||
|
|
|
||
|
|
<P>On the whole, it has worked out quite well. Yes, on occasion
|
||
|
|
somebody mistakenly responds directly to the author of a message when
|
||
|
|
they wanted to reply to the group. Most folks, however, seem to catch
|
||
|
|
on pretty fast to how it works, and seem to appreciate the flexibility.
|
||
|
|
Moreover, private responses mistakenly sent to the entire list have
|
||
|
|
become an almost unheard-of event.
|
||
|
|
|
||
|
|
<P>
|
||
|
|
<HR>
|
||
|
|
<ADDRESS>
|
||
|
|
<A HREF="../people/chip/index.html">Chip Rosenthal</A><BR>
|
||
|
|
<chip@unicom.com><BR>
|
||
|
|
</ADDRESS>
|
||
|
|
<P>
|
||
|
|
<IMG SRC="../graphics/small-back.gif" ALIGN="top" ALT="" WIDTH="16" HEIGHT="16">
|
||
|
|
<A HREF="index.html">Back</A> to the <CITE>Paperware Archive</CITE>.
|
||
|
|
<BR>
|
||
|
|
<IMG SRC="../graphics/small-up.gif" ALIGN="top" ALT="" WIDTH="16" HEIGHT="16">
|
||
|
|
<A HREF="../people/chip/index.html">Up</A> to Unicom Systems home page.
|
||
|
|
<BR>
|
||
|
|
<IMG SRC="../graphics/small-comment.gif" ALIGN="top" ALT="" WIDTH="16" HEIGHT="16">
|
||
|
|
<A HREF="/misc/cmntform.html">Let us know</A>
|
||
|
|
your comments, corrections, additions, suggestions.
|
||
|
|
<P><PRE>$Id: reply-to-harmful.html,v 1.20 2002/11/15 03:46:04 chip Exp $</PRE>
|
||
|
|
</PRE>
|
||
|
|
</BODY>
|
||
|
|
</HTML>
|