Thanks. A few additional follow-up clarifications. Mark Crispin wrote that:
> Normally, MUA edits of a message do not change the Message-ID. I don't know how to reconcile this comment with the language of RFC2822 as previously discussed which specifies that a Message-ID "...pertains to exactly one instantiation of a particular message; subsequent revisions to the message each receive new message identifiers". In any case my observations indicate that Outlook/Exchange 2000 does in fact change the Message-ID whenever a message is edited, both in the case where that message originated via "New Post in This Folder" and was subsequently edited (with the "Revise Contents" command) and also in the case where the message was delivered via SMTP and was later edited (with the "Edit Message" command). And I must interoperate with OE2K. While the Outlook/Exchange Message-IDs are rather lengthy there does not appear to be any information which is common between 2 edited messages, i.e. I can't find an unchanging UID sub-encoded within and it looks like it's just a system or folder-specific GUID value concatenated with an incrementing counter (see examples below). So, unfortunately, I can't figure out how to apply your comment that "a Message-ID remains a pretty good way to identify a message" other than, possibly, as a hint in certain cases (Outlook-edited messages unfortunately not being one of them). Note that Larry Osterman's comment about the public store vs. a users' private store while informative wasn't directly applicable to my situation. My system provides weblog-style views of users' private (server-based) stores as well as IMAP public folders. So I was using "public" not in the IMAP sense of anonymous access being enabled for such folders but in the more general sense that a user wanted to enable the weblog-style view of this particular folder. I.e. the public consumers of the information wouldn't have the associated IMAP account or password information, and might not even have visibility into the IMAP folder name space. Arnt Gulbrandsen wrote that: > You have two messages... The second is an edited > version of the first... both the message-id and body text may > have changed during the editing... I have a hard time understanding > how these two messages can be thought of as being the same. There > seems to be no invariant property. What am I missing?... If everything > can change, do you want the URL to remain unchanged? I'm not sure I can answer this properly but yes, I need the URL to remain unchanged even though the message body text may have changed. Once again the user model is an association of an original publication date and author (the invariant properties) with content which can under certain circumstances change, and what is desired is to retrieve the latest version of the associated content. This is for example the Outlook/Exchange user model and in Outlook/Exchange you definitely do not have two messages because the Outlook/Exchange editing process expunges the original version. This is also the user model presented by many bulletin-board content publishing systems. However, if you want to view the original vs. edited content as two "different messages" at some epistemological level, I cannot disagree. IMAP certainly views them as different messages since they have different UIDs and Message-IDs. But since only one entity is visible to end users they will most probably think of the original+edits as comprising one datum, e.g. "last Tuesday's recipe post", especially since the edits we are talking about are, in practice, mostly corrections. Conventionally, an "Edited On:" annotation is often provided, although as a side note there does not seem to be a way to obtain this metadata via IMAP from Outlook/Exchange 2000 since that system appears to fake all the IMAP-visible dates for edited messages. Since the word "message" is used in some very specific ways, and leads to some confusion at least on my part, I prefer to use a different term, like "post" to describe the datum that I'm talking about; however, "message" seems to be the term of choice in this forum. --Bill McCoy Outlook 2000 Message-ID examples: original Message-ID: <[EMAIL PROTECTED]> edited Message-ID: <[EMAIL PROTECTED]> Message-ID of previously most-recent item in the same folder: <[EMAIL PROTECTED]>
