Dovecot UIDs and POP.

[Ionel]

On 25.09.19 12:29, Sami Ketola via dovecot wrote:
> 
> 
>> On 25 Sep 2019, at 4.52, Plutocrat via dovecot <dovecot at dovecot.org> wrote:
>>
>> On 24/09/2019 10:14 PM, @lbutlr via dovecot wrote:
>>> Did the target machine already have the user setup? I think dsync wants to sync mailboxes between configured and working servers with users already defined.
>>
>> Yes, of course. And the directory structure was pretty much identical between the two. Which was how I was able to write and run the rsync script. 
>>
>> I think at this point, I'm past the dsync problems. That window has closed, and the migration is done, albeit with this irritating re-downloading of email with POP problem. However I'm still keen to get to the bottom of how this whole UID/UIDL/POP3 transaction takes place, so I can understand it for the future, and prevent it happening again. I'm guessing it would be a useful addition to the dovecot documentation as well. 
> 
> If you want to keep the data complete then the only proper way to do the migration is dsync. Specially since you now were migrating dovecot to dovecot.
> 
> imapsync does not retain imap uids or pop3 uidls. all users would need to clear their local caches.
> 
> Sami
> 
Very interesting thread, since I was about to perform the migration in
the next few days. I was operating under the assumption that imapsync
would retain both imap uids and pop3 uidls. According to Sami's post
this is not the case. This begs the question which path to take. The
source server is dovecot, albeit a very old version with no dsync (we're
talking dovecot 1.x.x).

Any ideas?

Thanks
Ionel