I am transitioning from a Linux box using an IMAP server to a 2007 Exchange server for a user base of less than 50. Many of these users have thousands of emails stored in many folders within the "Postfix/Dovecot" server. I have been exploring the different paths to migrating these folders and have not come to a clear path forward. I did explore the use of "Microsoft Transporter" but have yet to get it to function properly. Any advice or experience in the area would be appreciated.