On 2018-02-05 at 10:09, tomas@tuxteam.de wrote: > On Mon, Feb 05, 2018 at 09:44:43AM -0500, The Wanderer wrote: > >> On 2018-02-05 at 09:32, David Wright wrote: > > [...] > >> > :0 Wh: $HOME/msgid.lock >> > | formail -D 199999 $HOME/msgid.cache >> > >> > I used it for years. > >> I don't parse this well enough to understand what it would do, and I >> don't know where to find a procmail reference which would let me read up >> on it easily enough to understand quickly. Could you clarify? > > The trick is in formail (contained in the package procmail). Formail is > a pretty generic mail parser which can be used to filter mails (or parts > of mails) according to different criteria. Option -D instructs it to set > up a Message-ID cache to drop duplicate mails (duplicate in the sense of > Message-ID, that is). The number after the -D limits the cache's length. That wouldn't produce the behavior I want, though. Whether or not a "duplicate" private copy (or probably not actually duplicate, since mailing lists tend to modify other headers while leaving Message-ID alone) is inappropriate depends on context, and specifically, primarily on the sender's intent. There can be legitimate reasons to send a message both to mailing list and to a named recipient who is also subscribed to that list. For example, consider a high-volume mailing list, where many subscribers read only part of the traffic. If there's an ongoing discussion on that mailing list, and one of the participants wants to draw in a third person who also subscribes, it's entirely appropriate to CC a reply to that third party. However, if this were to happen with me, I would not want to receive *only* the mailing-list copy. I would want to receive both: the mailing-list copy to go into my local archive of the mailing list (and to be present in the mailing list's folder, so that it appears properly threaded with other replies), and the direct copy to draw my attention to the subject. (Although I would probably then seek out the mailing-list copy and reply to that. But that's a personal idiosyncrasy.) There are other possible complexifying scenarios, which distort the picture in other directions, but I don't have them ready to mind right now. What it boils down to is that dropping duplicate messages is only always appropriate when they are *complete* duplicates, in all headers (except possibly things like transmission path history). With a mailing list, that's rarely if ever the case. -- The Wanderer The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man. -- George Bernard Shaw
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