X-Advice Header Field Proposal

revision 3

X-Advice is a proposed message header field for providing hints about the importance and urgency of the message. Perhaps someday it will be called Advice.

Syntax

X-Advice: importance read urgency

importance is one of the words: perhaps should must

urgency is one of the words: whenever soon now

There may be arbitrary white space separating the three words in the X-Advice header field, but they must be in all lower case. The name of the field itself, X-Advice, is case-insensitive as required by RFC 822.

Semantics

The importance word is intended to provide a rough indication of how important it is for the recipient to read the message.

The urgency word is intended to provide a rough indication of the time-dependency of the message. Some messages lose relevance or purpose if they are not read soon enough.

Importance and urgency are orthogonal, as illustrated in the examples below.

No precise definition of the words is provided. The author of the message should select them based on their usual English connotations, and his/her knowledge of the recipient (if any). It is expected that the author will often have to “round off” to the nearest word.

The absence of an X-Advice header has no meaning; there is no default value. Human senders and their mail programs are discouraged from using default values. If the human sender has offered no advice for a particular message, then no phony advice should be present in the message.

Examples

X-Advice: perhaps read whenever
Check out this Dilbert cartoon.

X-Advice: perhaps read soon
I'm sick of watering this plant. If nobody wants it, I'll throw it away.

X-Advice: perhaps read now
It's snowing outside.

X-Advice: should read whenever
Read the ACLU vs. Reno decision. It's very well done.

X-Advice: should read soon
Could someone please record Star Trek tomorrow?

X-Advice: should read now
I'm going to get dinner. Want to join me?

X-Advice: must read whenever
You can pick up your final paycheck in room 324.

X-Advice: must read soon
The final exam is this Friday at 3:00pm.

X-Advice: must read now
We're all here for your presentation. Where are you?

Rationale

The primary motivation of this header field is to help automatic mail handlers make intelligent decisions about whether to biff (notify) the recipient when a message arrives. Presumably, the user could specify a policy based on all sorts of things, such as the time of day and various header fields, especially the From, To, and X-Advice fields.

A low-resolution space is used (only three values in each of two dimensions) in order to make selection of the appropriate values easy for the author. Higher resolution would allow more expressiveness, but if too much mental effort is required to choose the proper advice, no one will bother to include the field at all.

Words rather than numbers are used so that the field can be intuitively intelligible to humans, even if they are not familiar with it. This has the unfortunate side-effect of being biased towards English, but everything on the Internet is already biased towards English.

Lower case is required so that parsing is simple.

(end of proposal)


See Also

RFC 1327 and RFC 1911 define an Importance header which provides a subset of the functionality of X-Advice. It is a standard header for messages converted from X400 mail systems, experimental otherwise.

Feedback

Send comments regarding this proposal to my email address.

Experience

(as of Fri 21 Feb 1997)

I've been including X-Advice headers in most of my outgoing mail since June 1996, and I've been logging selected header fields of outgoing messages since November 1996. The statistics appear below.

I have set up my editor so that I can insert any of the nine X-Advice headers with three keystrokes (“*sn” for “X-Advice: should read now”, etc.), which makes using them quite painless.

The biggest problem I've faced is choosing the advice for messages with multiple recipients. Fairly often in a group-reply, I want to say “should” to the author of the message I'm replying to, and “perhaps” to the others, but I currently have no way to do that. In such cases, I have been omitting the X-Advice header. I welcome thoughts on this issue.

Statistics gathered on all non-test mail sent by amc between
02:00:43 GMT Wed 20 Nov 1996 and 02:50:16 GMT Fri 21 Feb 1997.

             messages:  639 #################################################
     x-advice headers:  463 ####################################

perhaps read whenever:   38 ###
perhaps read soon:        8 #
perhaps read now:         0
 should read whenever:  183 ##############
 should read soon:      169 #############
 should read now:        38 ###
   must read whenever:    3
   must read soon:       24 ##
   must read now:         0

perhaps read:            46 ####
 should read:           390 ##############################
   must read:            27 ##

        read whenever:  224 #################
        read soon:      201 ###############
        read now:        38 ###

Acknowledgements

I got the idea of using a header field to provide hints to biff-like programs from Eric Stuebe, though I don't know whether he endorses this proposal, or if he's even interested in standardizing such a header field.


[AMC]  Prepared by Adam M. Costello
 Last modified: 2001-Aug-29-Wed 00:22:43 GMT
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