[Dovecot] sdbox-format and sa-learn(spamassassin)

Hello,

is it somehow possible to use sa-learn on sdbox-mailboxes? Maybe i can use dsync to "mirror" the mailboxes(only the spam-subfolder) to another location and convert it to mbox or maildir and act then on it with sa-learn?

I know the antispam-Plugin, but until now no success, to get it running. So I think about an way, to learn via sa-learn on an file which i can process.

Regards Ingo