how to migrate mail messagges from ms. exchange to postfix

how to migrate mail messagges from ms. exchange to postfix?
Hi, I have to migrate e-mail messagges from a ms exchange server to a postfix server.

I have found nothing, the only thing I have in mind is to use fetchmail on the postfix server to get the e-mail messagges from the ms exchange server.

Is this correct?

Are there other methods, like "copy" e-mail from one machine to the other?

Which format are the exchange e-mail stored in?

Thanks in advance.

I have no idea what format Exchange uses to store emails, so I think fetchmail or getmail would be the best options.
http://www.howtoforge.com/debian_etch_fetchmail
http://www.howtoforge.com/debian_etch_getmail

Fetchmail can only be used for mail in transit, you need to use imapsync to do the migration it will preserve all the message flags.