Best way to move mail from one server to another

[Michael Slusarz]

Sami is correct.  imapsync loses data.

Source -> imapsync -> destination : the mailboxes are different to an IMAP client
Source -> dsync -> destination (running Dovecot w/doveadm): the mailboxes are the same

You may not care that your users w/100,000 message mailboxes that have been cached on their client now have to invalidate that entire cache (and most likely re-download all of those messages).

So there is zero argument that, due to IMAP metadata loss, this is something that doesn't happen if dsync (or rsync) is used.

michael


> On September 4, 2018 at 9:45 AM Rick Romero <rick at havokmon.com> wrote:
> 
> 
>     Quoting Robert Schetterer <rs at sys4.de mailto:rs at sys4.de >:
> 
>         > > 
> >         Am 04.09.2018 um 17:18 schrieb Sami Ketola:
> > 
> >             > > > 
> > >                 > > > > 
> > > >                 On 4 Sep 2018, at 18.00, Robert Schetterer <rs at sys4.de mailto:rs at sys4.de > wrote:
> > > > 
> > > >                 Am 04.09.2018 um 16:52 schrieb Sami Ketola:
> > > > 
> > > >                     > > > > > 
> > > > >                         > > > > > > 
> > > > > >                         On 4 Sep 2018, at 17.47, Robert Schetterer <rs at sys4.de mailto:rs at sys4.de > wrote:
> > > > > > 
> > > > > >                         Am 04.09.2018 um 09:41 schrieb Sami Ketola:
> > > > > > 
> > > > > >                             > > > > > > > 
> > > > > > >                             imapsync always loses data
> > > > > > > 
> > > > > > >                         > > > > > > never saw this, be carefull by anounce such myths
> > > > > > 
> > > > > >                     > > > > > It is a fact. Imapsync works over IMAP only and IMAP protocol does not even support transferring all data. At most at least UID numbering will be lost and end users need to invalidate their local caches.
> > > > > 
> > > > >                 > > > > but using "looses data" might others think it also may fail with imap,
> > > >                 so be more detailed next time
> > > > 
> > > >             > > > UID number is also data that is saved on the IMAP backend. If that is lost then it's "lost data".
> > > 
> > >             Sami
> > > 
> > >         > > Sorry i migrated terrabytes of mail with imapsync and never had a
> >         problem, it works as designed, also with maildir rsync did a good job,
> >         what never worked as it should was dsync ,cause of bugs ,that may
> >         changed now
> > 
> >         so this is my answer to topic
> > 
> >         "Best way to move mail from one server to another"
> >          
> > 
> >     > 
>     https://imapsync.lamiral.info/FAQ.d/FAQ.Duplicates.txt
> 
>     Seems to use UIDs so that 'data' isn't lost.
> 
> 


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