[Dovecot] Migrating existing local Maildir structure to dovecot server Maildir

[Halim Issa]

On 16/11/2009, Andreas Ntaflos <daff at dword.org> wrote:
> On Friday 13 November 2009 15:00:09 Halim Issa wrote:
>> Hello,
>>
>> I'm about to migrate a number of existing users who have been using
>> POP3 with emails stored locally in KMail's Maildir format into an
>> IMAP solution based on Dovecot.
>>
>> Will it be possible to simply move all the KDE Maildir folders from
>> the local PCs to the Maildir folder on the IMAP server running
>> Dovecot and then have the emails accessible on the server, or will
>> this most likely mess up the Dovecot index files?
>>
>> If this causes index file trouble, is there any way to force a
>> re-indexing of all these files, or is there another recommended way
>> of migrating up to 7 years of email communication from local hosts to
>> the IMAP server, for later putting them in folders?
>
> I don't think the migration of the Maildir structure itself is the
> problem. Dovecot has no problem reading it, no matter where it came
> from, as long as it is a proper Maildir structure. Existing indexes
> should not be affected.
>
> The indexes that KMail writes, however, will probably not migrate well
> or at all. I do not know anything about the index format KMail uses but
> converting it to something Dovecot understands and accepts seems
> troublesome and difficult to me.
>
> This means that you can copy all existing, local Maildirs over to the
> server (you can even put them in subfolders in existing accounts) and
> Dovecot will read them just fine. But it also means that Dovecot will
> very probably present them to the user as new messages, never seen
> before.
>
> But do yourself a favour and test any procedure you plan on implementing
> properly and extensively before actually implementing it. Otherwise it
> could end up messy and irreparable.

Thanks much for your thorough answer! I'll make sure to test extensively.

One thing came to mind - would it be possible to use Dovecot and
Disconnected IMAP itself for the transfer, and perhaps thus keep the
indexes?
If I move the messages from the local mailbox to the IMAP mailbox from
within Kmail it should perhaps keep the status?

Also - is there any documentation anywhere (or tips on better google
search terms) on what is stored in these indexes? I suppose apart from
Read/New status, it also contains whether or not there have been
replies to the mail and on what date the email was replied to?

Thanks again!