One document matched: draft-ietf-drums-replyto-meaning-00.txt
Network Working Group C. Newman
Internet Draft: Reply-To-Meaning Proposal Innosoft
Document: draft-ietf-drums-replyto-meaning-00.txt November 1997
Reply-To-Meaning Proposal
Status of this memo
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Introduction
This is a candidate proposal for one way which the problems with
the reply-to header in email could be resolved. Under no
circumstances should this be implemented as it is only a candidate
for a solution and no decision has yet been made. This proposal
distinguishes the different incompatible uses of the Reply-To
header with a new Reply-To-Meaning header. This has the advantage
of being relatively simple, not invalidating most current practices
and allowing mail user agents to present more predictable user
interfaces.
1. Conventions Used in this Document
The key words "REQUIRED", "MUST", "MUST NOT", "SHOULD", "SHOULD
NOT", and "MAY" in this document are to be interpreted as described
in "Key words for use in RFCs to Indicate Requirement Levels"
[KEYWORDS].
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Internet Draft Reply-To-Meaning Proposal November 1997
2. Reply-To Current Practice
The Reply-To header is currently used for the following purposes:
(1) The author/sender can suggest a complete list of addresses
which should receive any reply (e.g., a review committee).
(2) The author/sender can recommend an address or addresses to use
instead of the "from" address for replies.
(3) The author/sender can post to multiple mailing lists and
suggest group replies go to only one of them.
(4) When the author/sender is subscribed to a mailing list, he can
suggest that he doesn't want two copies of group replies to
messages he posts to the list.
(5) A mailing list can suggest that the list is a discussion list
and replies should be sent just to the list by default.
Many current MUAs have undesirable results with one or more of
these uses. However, if the MUA knew the intent when the reply-to
header was added, the undesirable results can be eliminated.
Alternative proposals to this one have suggested that the meaning
of Reply-To be restricted to (1), (2) or (3) and that additional
headers would be added for any of the other uses deemed important.
3. Reply-To-Meaning Header
The Reply-To-Meaning header is used to indicate the intent when the
Reply-To header was added. It has five values: "any", "private",
"group", "non-list" or "list."
any
The "any" meaning indicates that the author/sender added the
reply-to header as a suggested target for any reply (e.g., use
1 above).
private
The "private" meaning indicates that the author/sender added
to Reply-To header as an address for private replies to use
instead of the "From" header (e.g., use 2 above).
group
The "group" meaning indicates that the author/sender added the
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Internet Draft Reply-To-Meaning Proposal November 1997
Reply-To header as a complete list of addresses where group
replies should be sent (e.g., use 3 and/or 4 above).
non-list
The "non-list" meaning simply indicates that the author/sender
added the reply-to header (e.g., any one of 1-4 above).
list
The "list" meaning indicates that the Reply-To header was
added by a mailing list (e.g., use 5 above).
The formal syntax using ABNF from message format standard:
reply-to-meaning-header = "Reply-To-Meaning:" 1*FWS meaning-keyword
meaning-keyword = "any" / "private" / "group" / "non-list" / "list"
/ extension-token
Unknown extension-tokens are treated as equivalent to no Reply-To-
Meaning header. Meaning keywords are interpreted in a
case-insensitive fashion.
4. Examples
Here are a series of examples of various uses:
From: Chris Newman <chris.newman@innosoft.com>
To: DRUMS mailing list <drums@cs.utk.edu>
Subject: I'll collect straw-poll responses
Reply-To: Chris Newman <chris.newman+straw-poll@innosoft.com>
Reply-To-Meaning: any
In this mailing list posting, the author has asked that all replies
go to his straw-poll address.
From: Chris Newman <chris.newman@innosoft.com>
To: DRUMS mailing list <drums@cs.utk.edu>
Reply-To: Chris's DRUMS inbox <chris.newman+drums@innosoft.com>
Reply-To-Meaning: private
This author has a special address for private replies to his
postings on this list. This might also be used by a someone with a
secretary to review incoming responses.
From: Chris Newman <chris.newman@innosoft.com>
To: DRUMS mailing list <drums@cs.utk.edu>
Reply-To: DRUMS mailing list <drums@cs.utk.edu>
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Internet Draft Reply-To-Meaning Proposal November 1997
Reply-To-Meaning: group
This author doesn't want private copies of replies sent to the
list.
From: Chris Newman <chris.newman@innosoft.com>
To: DRUMS mailing list <drums@cs.utk.edu>
Reply-To: DRUMS mailing list <drums@cs.utk.edu>
Reply-To-Meaning: non-list
This indicates that the author explicitly added the Reply-To header
and the mailing list didn't change it. Although meaning (2) can't
be distinguished from meanings (1), (3) or (4), this does give
assurance that the author will see replies if the Reply-To header
is used without the From header.
From: Chris Newman <chris.newman@innosoft.com>
To: DRUMS mailing list <drums@cs.utk.edu>
Reply-To: DRUMS mailing list <drums@cs.utk.edu>
Reply-To-Meaning: list
This indicates that the list is a discussion list and it added the
Reply-To header to direct generic replies to the list. There is no
assurance that the author is subscribed to the list. In addition,
if the author included additional lists or people in a CC header,
they probably won't see replies directed only to the Reply-To
header.
5. Interpretation in Common Reply Functions
Many user agents provide more than one function to construct a
default set of target addresses for replies. This section suggests
how Reply-To-Meaning can be interpreted by certain common reply
functions:
Private Reply
A private reply is intended for the author(s) or the
delegate(s) of the author(s). When there is no Reply-To
header, or the Reply-To-Meaning is "group" or "list" then the
From header is used as the default set of target addresses for
replies. When Reply-To-Meaning is "private", then the Reply-
To header is used instead of the From header. If there is no
Reply-To-Meaning, or Reply-To-Meaning is "any" or "non-list"
then the MUA can offer the user a choice between using the
Reply-To or "From" header.
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Internet Draft Reply-To-Meaning Proposal November 1997
NOTE: if a Reply-To header was constructed with intent (1) or
(3)-(5), and was used without warning in a private reply, then
the reply could be directed to more recipients than the user
intended and cause serious embarassment or other undesirable
consequences.
Group Reply (also known as Reply All)
A group reply is intended for all authors and recipients of
the original message. When there is no Reply-To header, it is
constructed by using the contents of the original From, To and
CC header as the default set of reply targets (with duplicates
and possibly the replying user's address removed). When
Reply-To-Meaning is "any" or "group" the Reply-To address is
used as the complete set of reply targets. When Reply-To-
Meaning is "private" or "non-list", the Reply-To, To and CC
addresses are used as the default set of targets. Otherwise,
Reply-To, To, CC and From are all used as the default set of
targets.
NOTE: This can result in undesired duplicate copies of a reply
when a list address is included which the original author was
subscribed to and Reply-To-Meaning is not added. However,
this definition assumes duplicate copies are less harmful than
risking the omission of the original author. With the
opposite assumption, if Reply-To-Meaning was "list" or absent
only the Reply-To, To and CC headers would be used.
Generic Reply / Gateway
A generic reply is simply a desire to reply to the set of
recipients most likely to want the reply. It does not specify
a preference for a "private" or "group" reply. This is also
the set of addresses that gateways are forced to convey when
the target mail environment has a single reply-target address
list. This is defined as the Reply-To header, if present, and
the From header otherwise. User agents which offer this
function should draw attention to the Reply-To header when
it's present. Reply-To-Meaning has no impact on this
function.
6. Mailing List Rules
When a mailing list receives a message it MUST NOT alter an
existing Reply-To header. If there is a Reply-To header and no
Reply-To-Meaning header, the list SHOULD add a "Reply-To-Meaning:
non-list" header.
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Internet Draft Reply-To-Meaning Proposal November 1997
Mailing lists SHOULD NOT add a Reply-To header when one is not
present. However, if they do they MUST also add "Reply-To-Meaning:
list." In the short term it is particularly undesirable to do
this, as it can cause problems for user agents which don't
understand the Reply-To-Meaning header. Such user agents may make
it difficult to construct private replies. In addition, if a
message is posted to several lists, generic replies and some older
user agents may fragment the conversation to a single list.
7. Pro/Con Analysis
Pros:
* This is a fairly simple proposal
* This does not invalidate most current practices, which minimizes
deployment problems.
* This won't cause problems for legacy gateways which will never be
upgraded.
Cons:
* This is an ugly design because it leaves Reply-To overloaded.
* Legacy mailing lists which change existing reply-to headers will
really mess things up.
* This opens up the possibility of permitting lists to add Reply-To
headers which could cause short term problems as discussed in
section 6.
* There is no way to redirect private replies to a non-author and
group replies to a different target in the same message.
8. Security Considerations
There are a number of cases where a private reply could be
misdirected to a large group of people. Although this proposal
reduces the chances of this happening, it remains important for
MUAs to draw attention to Reply-To headers and reply targets in
most situations.
9. Open Issues with this Proposal
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Internet Draft Reply-To-Meaning Proposal November 1997
The "any" meaning will force current user agents to change their
interfaces for private replies when "any" is present. This will
probably be controversial.
The severity of the pros and cons is probably controversial.
10. References
[IMAIL] Crocker, D., "Standard for the Format of Arpa Internet Text
Messages", RFC 822, University of Delaware, August 1982.
<ftp://ds.internic.net/rfc/rfc822.txt>
[KEYWORDS] Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, Harvard University, March 1997.
<ftp://ds.internic.net/rfc/rfc2119.txt>
11. Author's Address
Chris Newman
Innosoft International, Inc.
1050 Lakes Drive
West Covina, CA 91790 USA
Email: chris.newman@innosoft.com
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