sendmail+imap to postfix+courier-imap

["Fryclau" <fryclau fibertel com ar>]

I will move my mailserver from sendmail & imap to postfix +
courier-imap.
The reason is the authentication features with mysql.

The hard thing is move the mailbox to the new maildirs without losing
emails.

Is there anyway to do that well?? I think in fetchmail.. Could it be?
I don't want to lose any email so please send me an advice to do it
properly. 

Thank Redhat-List

Fryclau