[Dovecot] Transparent Migration from cyrus to dovecot

[Darren Pilgrim]

On 10/6/2013 1:56 PM, Ed W wrote:
> Make use of the proxy feature.  You can add a "server" entry into your
> userdb, that way you can literally move users over one by one and flip
> their server location.  You can easily test individual users and move
> them over individually.
>
> Works brilliantly

Second this.  Pair it with a snapshot-capable FS and you can migrate the 
bulk of data in the background, then do the stop cyrus delivery, offline 
cyrus, copy remaining differences, online dovecot, start delivery to 
dovecot steps in a matter of seconds.