[exim] Migration from Exim to MS Exchange

Hi

I need migrate a Exim server to a MS Exchange Server.
I have today +3000 mailboxes in Exim server, and if I migrate de users
connecting MS outlook by POP in Exim server and store de messages in a
Exchange Server or in PST locally I will spend much time.
Somebody knows as I a make to migrate this in a faster way?

ps.: forgive, my english is horrible.

Att

Jackson