[Dovecot] (slightly OT) syncing / migrating IMAP mailboxes

[Steffen Kaiser]

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On Tue, 28 Aug 2007, Gunter Ohrner wrote:

I used UW-Imap's mailutil with success, but to copy an existing Mailbox to 
a fresh one using just IMAP. This is not your case.

> So, does anyone have any pratical solution on how to migrate one IMAP
> mailbox to another? For various reasons I'd really prefer to go with a

Well, the first thing is how do you want to decide, which mails are 
"identical".

I have great success with Maildir-based mailboxes by simply running a file 
dupe checker across both mailboxes and delete the duplicates from the 
"old" one. There was pretty few stuff left.

Way back, when we had some mboxes among the Maildirs, I transformed the 
mbox to Maildir, crafted a perl script that extracted the message ID and 
- From line from the mails and deleted any dup from the "old" mailbox (and 
compared the body before, just to be sure).

> cannot seem to get reliably support from its authors and/or its user
> community... :-/

Be yourself.

You have to make your own rules about what you consider as "equal" 
messages, e.g. when the two mailbox syncs lay one month apart:

+ The user moved a message to another folder in the "new" mail store.
+ The user has the message multiple times in his mail folders. (Even 
within the _same_ folder). This can happen intenionally and not.
+ The "same" message arrived the user multiple times through different 
hops - the body and the essential headers (From, MessageID, To, ...) are 
the same, but not Received and "custom" headers (e.g. Virus scan notices).

I would not rely on another tool.

Bye,

- -- 
Steffen Kaiser
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