rsync sdbox, no new mails?

[Jakob Curdes via dovecot]

Hello, I had to restore a mailserver from a backup to replace a system 
with problems that is still live. I did a 1:1 restore as far as possible 
from a backup, then rsynced the /var/vmail/ directory, where we have all 
the mailboxes, in sdbox format.
So both directories should be the same. After syncing, I started 
dovecot. I can see the mails until to the point of the backup, but not 
the newer ones ,although they seem to be present in the "cur" directory.
I thought with sdbox it is all in the index files that have been 
transferred with the mails? Or am I missing a place that has to be synced?

Thank you for hints, Jakob