[Dovecot] importing plain mboxes to dovecot maildirs

[Radim Kolar]

Is there way to import old plain mboxes via dsync? It complains about 
lack of index files:

ponto:(admin)~>dsync mirror mbox:~/mail
dsync(admin): Error: Failed to sync mailbox sent-mail: Mailbox GUIDs are 
not permanent without index files
dsync(admin): Error: Failed to sync mailbox saved-messages: Mailbox 
GUIDs are not permanent without index files
dsync(admin): Error: Failed to sync mailbox sent-mail-feb-2012: Mailbox 
GUIDs are not permanent without index files