Recommended tool for migrating IMAP servers

[Sami Ketola]

> On 4 Dec 2017, at 19.59, Webert de Souza Lima <webert.boss at gmail.com> wrote:
> 
> On Mon, Dec 4, 2017 at 9:16 AM, Sami Ketola <sami.ketola at dovecot.fi> wrote:
> 
>> 
>> With every other tool you will face end users needing to  invalidate their
>> local caches and
>> redownloading all headers if not also all mail bodies.
>> 
>> Sami
>> 
>> 
> I don't think so. Been using imapsync for large scale migrations from
> external servers to our dovecot setup. Users don't even see it when the key
> is switched (DNS changes).
> Go for it.

You are wrong. There is no way to assign IMAP UID:s over IMAP protocol. It simply does not support it.
With imapsync there is absolutely no way to preserve them and you will face problems with IMAP UID:s
not matching the cached mail anymore.

Trust us. We have run multiple migrations at scale of 10+ million users.

Sami