On Fri, Dec 9, 2011 at 5:25 PM, Jeffrey Honig <jch(_at_)honig(_dot_)net> wrote:
I have my fetchmail scripts ignore messages with a duplicate messageid
(using a history of messageids I've received during the last 30 days or so)
to avoid duplicate mail.
Depends on what you mean by "duplicate". From a mail archiving perspective,
you can have multiple messages with same message ID, but can be considered
different messages, even if the "content" is the same.
Example: Mail that is sent to individuals and mailing list(s). Mailing
lists typically add additional headers (e.g. List-*) and custom footers,
so the message that is received by list subscribers is not identical
to versions received directly from the original sender.
It is probably too much to assume that everyone would not have duplicate
copies of a message with the same messageid. Some people may have valid
reasons for this.
Archiving messages to mailing lists is a valid reason.
And there may be messages w/o a message-id.
This is the case for draft messages in nmh.
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