Non-destructive deduplication

[Aki Tuomi]

> On June 10, 2017 at 10:30 PM Tristan Miller <psychonaut at nothingisreal.com> wrote:
> 
> 
> Greetings.
> 
> I use Dovecot 2.2.29.1 as my IMAP server.  Owing to a bug in my mail
> client [1], several unique messages (mostly in my Sent folder) have
> duplicate Message-ID headers.  Dovecot itself doesn't seem to be
> bothered by this, though my mail client is confused by the false
> duplicates.  (It screws up the threading display, and results in data
> loss when I run the client's deduplication filter.)
> 
> I would like to change the Message-ID headers in the "duplicate" message
> files stored in my IMAP server so that they are unique.  I realize that
> this has disadvantages of its own, but I can't think of a better
> alternative.
> 
> So this leads me to two questions:
> 
> 1) Will Dovecot get confused if I simply open the message files in a
> text editor and manually change their Message-ID headers?  If so, how
> should I go about changing the Message-ID headers?
> 

Expunge the mails, then edit message-id's and import them back.

> 2) Does there exist any tool that will scan a maildir folder to find
> messages with duplicate Message-IDs, and automatically rewrite the
> Message-ID headers so that they are (probably) unique?  I could
> probably kludge together a quick shell script, but if someone's already
> gone to the trouble of writing such a tool and making it relatively
> robust, I'd rather use that instead.
> 

https://wiki2.dovecot.org/Tools/Doveadm/Deduplicate should let you expunge duplicate messages.

> Regards,
> Tristan
> 
> [1]
> http://www.thewildbeast.co.uk/claws-mail/bugzilla/show_bug.cgi?id=3828
> 
> -- 
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>                   Tristan Miller
> Free Software developer, ferret herder, logologist
>              https://logological.org/
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-