Duplicate suppression, other processing at split time

Duplicate suppression, other processing at split time

[David Z Maze]

If I wind up with the same message delivered to me twice, can I cause
the second message to get dropped at split time?  (In particular using
nnimap-split-fancy, but I could probably adapt other techniques people
have for doing this.)  Is other processing possible?

The particular problem I have is people sending messages without
Message-Id to multiple lists that I'm on.  Then Gnus sorts each of the
copies into each of the lists in the To: line.  But, since there's no
Message-Id, duplicate suppression never trips, and I wind up seeing
n^2 copies of the message; if n is 3 or 4 this gets really annoying.
Another part of our local mail pipeline inserts a string that has the
right properties to be the Message-Id, so first I'd like to copy that
header value to Message-Id if there isn't already one, then do dup
suppression by Message-Id, *then* split.

(Procmail scares me -- I understand what Gnus does, and
nn*-split-fancy is kind of elegant in its own way -- but I think it is
an option, if this is something easy to do there.)

Thanks,

  --dzm

Re: Duplicate suppression, other processing at split time

[David Z Maze]

David Z Maze <dmaze@mit.edu> writes:

> If I wind up with the same message delivered to me twice, can I cause
> the second message to get dropped at split time?  (In particular using
> nnimap-split-fancy, but I could probably adapt other techniques people
> have for doing this.)  Is other processing possible?

Having Read The Fine Manual a little more, it looks like this is very
straightforward to do for nnmail, but not necessarily so
straightforward for nnimap.  Can I do info://gnus/Washing+Mail as
nnimap splitting happens?

  --dzm

Re: Duplicate suppression, other processing at split time

[Ted Zlatanov]

On Wed, 01 Jun 2005, dmaze@mit.edu wrote:

> David Z Maze <dmaze@mit.edu> writes:
> 
>> If I wind up with the same message delivered to me twice, can I cause
>> the second message to get dropped at split time?  (In particular using
>> nnimap-split-fancy, but I could probably adapt other techniques people
>> have for doing this.)  Is other processing possible?
> 
> Having Read The Fine Manual a little more, it looks like this is very
> straightforward to do for nnmail, but not necessarily so
> straightforward for nnimap.  Can I do info://gnus/Washing+Mail as
> nnimap splitting happens?

I don't think that will work.  You could try, however, to add
duplicate suppression to the gnus-registry and use that; I am thinking
of something like this in the fancy split:

(: gnus-registry-split-duplicates "duplicates") ; or 'delete

The problem is what to do when the message has no message-ID of its
own, as you mention.  It should be pretty easy to generate a unique
message-ID for the registry based on unique information such as the
subject and sender, while preventing collisions from multiple messages
with the same subject and sender.  Perhaps the time or the message's
backend information could be used.

Ted



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Re: Duplicate suppression, other processing at split time

[David Z Maze]

David Z Maze <dmaze@mit.edu> writes:

> If I wind up with the same message delivered to me twice, can I cause
> the second message to get dropped at split time?
>
> (Procmail scares me -- I understand what Gnus does, and
> nn*-split-fancy is kind of elegant in its own way -- but I think it is
> an option, if this is something easy to do there.)

It turned out that dup suppression is something explicitly mentioned
in procmailex(5), so I'm doing it (along with adding a Message-Id if
need be) in procmail.

  --dzm