[Dovecot] sync re-copies emails assigning new UIDs

[Anand Kumria]

Hi,

I have been (attempting) to transition a company from in-house dovecot 1.x
to a hosted dovecot 2.2 setup.

I am running the doveadm sync command, and for the four mailboxes have been
blocked -- sync'ing seem to be copying the same mails, over and over (note,
initially I was using doveadm backup but my reading has indicated that
'doveadm sync' is better)

Example:

# date && doveadm -v -o imapc_user=kaye at example.com -o
imapc_password=*pass* -o imapc_host=imap.example.com -o imapc_port=993 -o
imapc_ssl=imaps -o imap
c_ssl_dir=/etc/ssl -o imapc_feature=rfc822.size -o imapc_ssl_verify=no sync
-1 -R -u kaye at example.com imapc:
Sat Aug  3 09:05:37 UTC 2013
[...]
dsync(kaye at example.com): Info: copy from INBOX: box=INBOX, uid=5306,
msgid=<FB3A2E1C62B148F8B057476BDCBB4A9B at THENORMANS>, size=13544
dsync(kaye at example.com): Info: copy from INBOX: box=INBOX, uid=5307,
msgid=<006b01ce8dad$b8864930$2992db90$@com.au>, size=10163563
[...]
dsync(kaye at example.com): Info: copy from INBOX: box=INBOX, uid=5311, msgid=<
cm.083930.bijjdjk.jdkimlhij.r at createsend5.com>, size=46658
[...]


# date && doveadm -v -o imapc_user=kaye at example.com -o
imapc_password=*pass* -o imapc_host=imap.example.com -o imapc_port=993 -o
imapc_ssl=imaps -o imapc_ssl_dir=/etc/ssl -o imapc_feature=rfc822.size -o
imapc_ssl_verify=no sync -1 -R -u kaye at example.com imapc:
Sat Aug  3 10:01:48 UTC 2013
[...]
dsync(kaye at kamdha.com): Info: copy from INBOX: box=INBOX, uid=5324,
msgid=<FB3A2E1C62B148F8B057476BDCBB4A9B at THENORMANS>, size=13544
dsync(kaye at kamdha.com): Info: copy from INBOX: box=INBOX, uid=5325,
msgid=<006b01ce8dad$b8864930$2992db90$@com.au>, size=10163563
[...]
dsync(kaye at kamdha.com): Info: copy from INBOX: box=INBOX, uid=5329, msgid=<
cm.083930.bijjdjk.jdkimlhij.r at createsend5.com>, size=46658
[...]

The exact same number of emails (some in the INBOX, some in the Sent
folder) are transferred each time.

In this case, I've firewalled the origin - so their entire mail system is
stopped whilst I do the transfer just in case modifications of IMAP flags
or additional delivieres might have been the problem.

I am using Dovecot v2.2.4; is this normal expected behaviour? If so, what
is the best way to ensure that a migration is done without data loss.

If this isn't expected, has anyone else seen this kind of error before?

Thanks,
Anand